I wish I had a digital camera to show you a pic. Maybe someone else here can help me out and post a pic?
A spacer is a piece of plastic roughly 1/2" thick by 2 1/4" long by 1 1/2" wide. It has screw holes in it that line up perfectly with your sight screw holes and the holes on your riser. You put the spacer between your sight and riser and mount your sight to the bow. What it does is it brings your sight out to the right a little over 1/2" which normally gives you plenty of room to sight in and still have your sight pins in the middle of your sight guard. You can get one at any proshop. I also place a thin piece of rubber between the spacer and riser and spacer and sight for dampening purposes.
Hope this helps!
I'm gonna leave all comments pertaining to your proshop saying that "paper tuning a single cam bow is useless" to everyone else.