Hi,
I'm gearing up for an incoming DH game and helping some of the players finish up their characters. I have two psykers now, and the player of one asked me just what design the sanctioning brand has and where it can be. That got me thinking, and the fact that it's in the gear sections makes me wonder if it's not a "memento" rather than a brand in the first place. Now, I consider the word "brand" quite literal, but the Dark Heresy novels (for all they are worth) have a sanctionite who's gone undercover have an affair with a rogue psyker. Considering that sex (and therefore nudity) was involved, and there was no mention of the brand being somehow obscured, I expect that means a psyker can either not have any visible identifying mark, or the author didn't do his research.
For now, I'm leaning towards allowing a mark where it can easily be accessible for inspection - face, hands, shoulders or chest. However, this is just my gut feeling - does anyone here have specific rules or examples of how it works in your games?