Im pretty sure the rear sight is adjustable. But before you adjust it, what type of problem are you having?
When I first got my CW 9, I was shooting low and left. Turns out it wasn't the gun, it was me. I was pulling the trigger and jerking the gun causing the problem. I learned how to squeeze the trigger and the gun shoots much better now. Kahrs come from the factory shooting pretty straight, for what they are they have amazing accuracy.