I have a post on my byc page about this that is mostly tongue in cheek, but has a degree of seriousness -
I have used the RBPNM.. with a small degree of success, but my flock had an advanced case of picking, so it wasn't quite enough.
Practical advice: stop it fast - if they are doing it after establishing a pecking order, it's usually because something in the husbandry is not quite right, (edit: mine was also a case of quite neurotic individuals) Feed higher protein for a while, use lights, try the Rooster Booster products (they also have vit. b supplements and minerals you put in their water that I have had great success with - ) If you use the Pick No More... USE GLOVES if you have to touch it to apply it!! Otherwise your fingers will be purple for days.
I had to reapply it fairly often, but the capsaicin is there - works well.
If you can't get the picking to stop with these things, there are "pinless peepers" that you can get from poultry supply stores online. Everyone who uses them swears by them because they 'block' the front vision of the wearer, and they cant hone in on feathers. Amazingly (I used these too) it does not affect eating or drinking or laying or make them bump into things - just doesn't allow them to fixate. There is a BYCer here who uses them for 6 weeks (glues googly eyes on them, it's HYSTERICAL) and it seems to break the pattern.
Good luck!