Leave a small space about 1/8 inch between the rest and the leather you use on the side of the site window to help in feather clearance. You might also want to place something short [ the width of the rest material]and small i diameter like a tooth pick or match stick under the rest between it and the shelf right above where the web of your hand contacts the riser. This helps cut down on arrow drag as it passes over the rest.
Hope this helps and is clear enough otherwise give me a call at 360-989-6355 and I'll try to help by phone.
Gene