I used an 11x14 with a 5x7 opening and it turned out fabulous! I didn't use tape, just traced where the frame hit the mat with a pencil (lightly), and wrote in the part that would be hidden "please don't sign here" and also, I noted how I wanted the picture orientated (portrait/landscape)! If using colored markers, I recommend not taking the yellow one! The signatures with yellow don't show up very well!