I order mine from a supplier. They are expensive by some thinking but a good clean logo is important. It works out to very little per knife.
I would do a search for etching stencils or something like that. I hate to recommend one since I don't know but one. I know there are more but in fairness some might prefer other suppliers than the one I use.
Get everything clean with denatured alcohol and go for it. I set mine on "3+" and let it sizzle.