On the garment, mark the placement of the slot. This will either be lengthways on the center back or parallel to the neckline. Ensure to check your placement is straight and level. If you are creating the adaptation for a harness, put the harness on your dog, then the garment to be altered and find the location of the harness toggle to better mark the garment.
Lay the SLOT BINDING RIGHT SIDES together with the garment. Pin and stitch as shown by the central rectangle on the pattern piece.
Com uma tesoura pequena afiada, snip along the inside length of the rectangle, forking out into the corners (be carful not to snip through the stitches).