Cut 4 strips the length of the quilt plus extra for mitering the corners. Measure the scallop depth adding 1/4" for seam allowances and bit extra for safety. Double this number to get the cut width. Press facing in half lengthways as shown above
I pre-quilted each scallop so that I would have the curved shape showing through to the back of the quilt (Marci stay stitched around her hexagons on the machine).
Lay the facing on the right side of the quilt with the raw edges matching and pin in place.
Turn the quilt to the back and, starting from the exact corner of the quilt, sew along the side of the quilt using a small stitch and using the quilted scallop line as a guide (I stitched just over a 1/4" away from this line). Make a pencil mark at each point between the scallops to show where to stop and turn for the next scallop.
Finish sewing exactly at the far end corner of the quilt and after each facing has been attached trim the excess fabric away and clip the inner points. Very sharp (Kia) scissors are essential for this and be careful not clip through the stitches.
See the video mentioned above to see how the corners are mitered (I pressed the 45 degree angle on each facing end but forgot to take a photo).
Turn the scallops inside out and press the edges. The facing will now be at the back of the quilt and can be stitched down along the folded edge, hand stitching the mitered corner using the pressed lines as a guide.
I trimmed a bit too much bulk from the first corner before turning it over, which made sewing the miter a bit fiddly. I didn't do that again, proving you always learn from your mistakes!
And here's the result...Much easier than I expected!