I agree with Mike and Pichou - I've used about eveything out there over teh last 40+ years for dying bone and antler (essentially the same) and have found the Fiebings Leather Dye (I use the regular not the Oil Dye) to be the best by far. PP works OK, but over time it tends to fade and get ratty looking especially if not properly neutralized.
Too see the various "looks" you can get with leather dye on antler you can take a look at my website - peruse teh Galleris - all of the antler handles (a mix of deer, Sambar Stag, and elk) have been dyed with leather dye.
Some suggestions:
1) to get that yellowish/brown often seen on old pieces I use thinned British Tan or a mix with light Brown. FWIW - I buy Dark Brown and thin only the amount needed at a time with alcohol to the shade I want - saves on inventorying several shades of brown. If anything start out light and darken as needed/wanted. Each and every piece of antler is different.
2) Another option - dye with Black, Dark Brown or a mix of the two first and then quickly wipe off the excess on the surfaceleaving the dark in the cracks and grooves. Then apply a coat of lighter dye of you choice and let it set for 12-24 hours. Rub down with a coarse cloth such as old jeans of canvas.
3) You can also change the look by rubbing it down after drying with 4/0 steel wool - go slow and easy until you get the look you want. If you got too far re-apply. I tend to get the most natural aged look by doing a mix of #2 and #3, and re-applying several times.
4) For best color fastness soak the antler in the dye for a week and then let dry for 48-72 hours.
5) Some folks say you need no finish at all but I prefer to add one - I use my onw period violin type varnish - the closest commercial finish to that is Tried and Trues' Oil Varnish - a mix real boiled linseed and rosin. Apply two or three LIGHT coats letting dry thoroughly in between - hang in the sun and where it gets air movement (or use a fan on low) for drying.
Final word - if you don't like the look - clean off the dye with 4/0 steel and acetone, but if there is any porous section they tend to soak up the dye and it's hard to undye them.