I've done several Hidden Wells quilts, and I do my borders just like any other quilts I do. Measure across the middle both for the width and the length, pin the borders in place, and stitch! It will ease in and ripples will disappear if you by chance have any, which you really shouldn't have, if you haven't stretched on the biased edges. My favorite one I've done so far was all in neutral colors... a gift for a dear friend of mine, which I called "Sands Of Time", which describes our friendship.