I trim mine flush with the edge on the bow's back. I use a new olfa blade, and run it at about a 45 angle. If the blade isn't sharp, the skin tends to rip. I also found if you wrap the skin around the edge, it just won't stick. I usually gently sand the finished edge just a bit, going with the grain of the skin, from head to tail. If any little edges pop up, I just tack them down with a bit of super glue. Finish with whatever you normally use... I like truoil or poly.