Place the ruby lith/matboard or black material on top of the glass of the contact printing frame. Make sure you don't have too thick of glass.

On the side of the glass where the negative is put against, use tape and create somewhat of "stops" to butt the negative and paper against so they match up with the mat overtop.

This way, you just leave the top mat always on the glass, and all you do is lay the negative and paper in the contact frame and close it up to expose. VERY SIMPLE.