These are some excerpts from the Gor novels regarding branding, copied from the old Valnor forum.

Branding on Gor

“Oh, no!” I cried, “No, no, no, no!”
My captor had gone to the brazier and, with the leather glove, and another, too, with two hands, withdrawn the white hot iron. I felt the heat of it, even feet away. “No!” I screamed.
“No!” Two men, large men, strong, held my left thigh immobile.

I looked into the eyes of my captor. “Please, no! I wept. “Please, no!”
Then, head down, helpless, held, I was branded a Gorean slave girl.

The marking, I suppose, took only a few seconds. That is doubtless true. Objectively I grant you the truth of that. Yet a girl who has been marked finds this obvious truth difficult to accept psychologically.

Perhaps I may be granted that those seconds, seems very long seconds.
For an hour it seemed I felt the iron. It touched me firmly, kissing me, then claiming me.

I screamed, and screamed. I was alone with the pain, the agony, the degradation, the relentless, hissing object, so hurting me, the men. Mercifully they let me scream. It is common to let a girl scream, a Gorean kindness, while she is being marked with a white-hot iron. Afterwards, however, once the iron is pulled out of her body, and she is fully marked, Gorean males are less likely to accord her such consideration for her feelings. They are less likely, then to be so indulgent with her. This makes sense. Afterwards, she is only a branded girl.

It begins swiftly, almost before you can feel it. I felt the iron touch me almost instantaneously, crackling, flash through me outer skin and then, firmly, to my horror, enter and lodge itself fixedly in my though. It was literally in my body, inflexibly, burning. The pain then began to register on my consciousness. I began screaming. I could not believe what was being done to me, or how much it hurt. Not only could I feel the iron, but I could hear it, hissing and searing in the precise, beautiful wound it was relentlessly burning in my thigh. There was an odor of burning flesh, mine. I smelled burning, as of a kind of meat. It was my own body being marked. I could not move my thigh. I threw back my head and screamed. I felt the iron tight in my body, then to my horror, pressing in even more deeply. The marking surface of the iron, then lay hissing, literally submerged, in my flesh. I could not move my thigh in the least. I threw my head from side to side, screaming. The marking surface of the iron is some quarter of an inch in depth. It was within my flesh, lodged there, submerged, hissing and burning. Taking its time, not hurrying, it marked me, cleanly and deeply. Then, swiftly, cleanly, it withdrew.

I smelled burned meat, my own, the men released my thigh. I began to choke and sob. Men regarded the mark. My captor was commended on his work. I gathered I had been well marked.

Slave Girl of Gor, pages 57-58

The Branding Rack

I ripped the bit of cloth away from her hips and threw her against the rack. I swung shut the two heavy bands and with the two twist handles, tightened them on her thigh. I took her wrists and pulled them forward, to the two posts, some 6 inches apart, part of the branding rack, putting them in the snap bracelets which dangled there, one from each post. These are simple mechanisms. It is quite easy to open and shut them, and it may be done with a snap of the finger, one for each bracelet. As the bracelets are situated, some inches apart, of course, and as the snap is on each bracelet itself, at the wrist, the girl herself cannot get her finger, of either hand, on the mechanism. Others may open them easily; She, on the other hand, is perfectly held. I took again the twist handles. I turned them extremely tightly. “Oh, oh,” she cried. She pulled futilely at the snap bracelets. Then I again turned the twist handles.

“Please!” she cried.
“Be quiet,” I told her. She bit her lip.
I tightened the handles more and put in the locking device, that they might not slip back. Her thigh was absolutely immobile.

“I see you like a left-thigh-branded girl,” said Hassan.
The girl can writhe in the rack or squirm, or scream, but the held thigh will not move. It is held for the kiss of the iron.

The Brandings

This is performed when a girl is reduced to slavery for the first time, or if she already wears a brand and her new Master wishes to re-brand her. It is common Gorean practice to allow the slave the luxury of screaming, since it is in effect her final act as a free person.

The branding of Tarna

With a heavy glove, Hassan pulled an iron from the brazier. “What do you think of this brand?” he asked.
It was the Taharic slave mark.
“It is beautiful,” I said. “But let us assure ourselves that this will be a common slave, one fit to sell north.”
“A good idea,” said Hassan. He returned the one iron to the brazier and reached for another. It glowed red. It was a fine iron, clean and precise. At it’s tip, bright red, was the common Kajira slave mark of Gor. Tarna looked upon it with horror.
“It is not yet hot enough, my pretty,” said Hassan. He returned it to the brazier.

In a few Ehn he removed the iron from the coals, and examined it. He then again replaced it. Shortly thereafter, however, for it must have been almost ready, he drew it forth again. It glowed white.

“You may scream and cry out, my pretty,” said Hassan, not unkindly.
She struggled in the bracelets, she watched the iron. Then she screamed. For five long Ihn Hassan held the iron, pressing it in. I saw it sink in her thigh, smoking and hissing. Then he, cleanly, withdrew it. Tarna was marked.
She sobbed, wildly. We did not rebuke her. I freed her thigh of the rack, She fell on her knees at the posts, sobbing. I freed her wrists of the snap bracelets. I lifted her, sobbing, in my arms.

The branding of Vella

I took her to the branding chamber, threw her into the device, and locked it on her thigh. Hassan was there and the iron was already hot. It was the same iron with which he had, the night before, marked the proud Tarna. It had been cleaned, with a solvent. One iron, properly cared for, can mark thousands of women. “No, Master,” she said, “please!” “Do you wish to mark her?” asked Hassan. “Yes,” I said. I would place the mark on her left thigh, above that of the four bosk horns. It would be the common Gorean female slave mark, fitting for a low girl, such as she, one who had not been fully pleasing.
I held up the iron, white hot, for the girl’s inspection.
“You will soon be branded, Girl,” I told her.
“Don’t brand me!” she cried. “Please don’t brand me!” She wept.
Hassan regarded her with interest.
“We are now ready,” I told her.
She looked at me, then at the glowing, white-hot marking surface of the iron. She watched with horror, as it approached her.
I held it poised at her thigh.
“Don’t!” she cried. “Don’t!”
“You are now to be branded, Slave Girl,” I told her. “No,” she screamed. Then I branded her. For five long Ihn I held the iron, pressing it in. I watched it sink into her thigh, smoking and crackling and hissing. It was a larger brand than that of the four bosk horns; I made sure it marked her more deeply. We three, Hassan, I and the girl, smelled the marked, burned flesh of her. Then, swiftly, cleanly, I withdrew it. Her head was back. She was screaming and weeping. “A perfect brand,” said Hassan. “Perfect!” I was pleased. Such a brand would be envied by the other girls. It would improve the sleek little animal’s value.
I removed the locking device, and spun loose the twist handles, releasing her thigh. I freed her of the snap bracelets. I carried her, naked, branded, weeping, to the small cell where I had thrown her tiny garment, to be retrieved later. I put her down on the straw. Her throat was bare, for I had had, the preceeding night, the collar of Ibn Saran removed from her throat.

The Location of a Brand

“Yes, left thigh,’ said Samos to one of the guards. I liked the left-thigh branded girl. A right-handed master may caress it while he holds her in his left arm.”
Beasts of Gor, page 25

“Where are we branded?” She said. “A girl is commonly branded on the left or right thigh,” I said, “sometimes on the lower left abdomen.”
Beasts of Gor, page 229

“Left thigh or right thigh?” he asked. “Left thigh,” said Ulafi. Slave girls are commonly branded on the left thigh. Sometimes they are branded on the right thigh, or lower left abdomen.”
Explorers of Gor, page 71

“I also checked certain less common brand sites, such as the lower left abdomen, the interior of the left forearm, and the high instep area of the left foot.”
Players of Gor, page 191

“I had seized her, half lifted her, and turned her from side to side, examining her slim, attractive thighs for the tiny brand which would confirm the matter. The most common brand sites, that on the left thigh, the favorite, and that on the right thigh, lacked slave marks. This determination, given the nature of her garmenture, could be instantly made. I then put her on her feet. “Oh!” she said. She was not branded on the lower left abdomen. That is perhaps the third most favored brand site. I then checked several other brand sites, such as the inside of the forearms, the left side of the neck, behind and below the left ear, the backs of her legs, and her buttocks. I even examined the insteps of her left and right feet. Her body was not branded.”
Renegades of Gor, page 124

But her left thigh worn no brand. Her right thigh, too, as I soon noted, did not wear the slave mark, nor did her lower left abdomen. These are the three standard marking places, following the recommendations of Merchant Law, for the marking of Kajirae, with the left thigh being, in practice, the overwhelmingly favored brand site.?
Fighting Slave of Gor, page 312

The thighs and the lower left abdomen are the brand sites recommended by Merchant Law.
Fighting Slave of Gor, page 349

A small guide to the most common Brand

The common Kajira brand or Kef, based on the description in Fighting Slave of Gor, book #14

“… a deep mark, a lovely mark, about an inch and a half high and a half of an inch wide… the design was rather floral. it consisted of what seemed to be a straight line, rather severe, with what appeared to be, adjacent to it, to its right, two fronds, curled and graceful…. the straight line is supposed to represent the staff of discipline and the two fronds the beauty of a woman. the significance of the whole, then, would be beauty subject to the staff of discipline…”

Brand: Slaves on Gor are branded, usually with a Kef, the Gorean equivalent of ‘K,’ the first letter of the words kajira and kajirus. Males slaves are branded with a block Kef, whereas the female slaves are branded with a highly stylized cursive Kef. Although many different brands can be found, with some Masters even choosing to design a unique brand for their slaves, the most common is the Kef.

“I have five brands,” said the metal worker, “the common Kaura brand, the Dina, the Palm, the mark of Treve, the mark of Port Kar.”
Explorers of Gor, page 70