does it matter where in reference to the riser or the distance between the cams you should set your knock? Everything I have read only reference that it should be "X" distance above your rest?

If it does not matter, than what direction could I move the knock point to get my sight to move down. Right now my sight is almost maxed out all the way up and I think it would be in my best interest to get the sight moved down some, but I want to make sure that if I move the knock point down some (and the rest) that the sight will move down as well?