KathyC9511 the only advice I can tell you is that I find the size of the scallops to be used just like I would have to adjust any large stencil. Lay out your quilt using larger dinner plates in the corners since they will be a quarter of a circle. Then measure the distance. Choose the size of scallop you want. If your distance is 80", then the best size would either be an 8" or 10" scallop. You have to also measure the other size and slowly decided which size will fit both sides the best.