In my experience, treatment of antler with linseed oil (or most other oils in fact) will make the antler go yellow(!) The black won't rub out if you carve it well. (I use oilpaint to fill up the tracks) Over time and use the tracks will fill up with dirt and sweat so even then they won't just dissappear.
Reindeer antler doesn't need any finish IMO because you can polish it to a high shine and it is fairly waterproof in itself.