GA,
Have no picture, but it's just a board about 8" wide with two straight, parallel sides, and some clamp blocks to hold a half ring in place. Board should be flat, of uniform thickness. Cut a strip of "gage paper" (mine is .004" thick) slightly narrower than the sled board thickness. Lock the rip fence and secure the paper against it with the edge of the board. The board is now parallel to the fence and .004" away from it. Place half ring on the board, against the rip fence and clamp in place. The half ring now extends .004" beyond edge of the board. Turn board end for end, position rip fence at exact width of the sled board, and make the cut. You have removed .004" of some of the half ring ends and none of the sled board. Check half ring ends to see that you got a full cut on both ends. If so, the ends should be flat and coplanar. If not, repeat. I like an 80 tooth carbide blade for this, but it's not essential. Hope this helps.