As I was finishing up this bath towel, I realized what I had done wrong.
Both the towel and the fabric should have been washed and pre-shrunk in the drier a couple of times before I sewed them together. D’oh! Now they will shrink at separate rates, and there will be puckering.
Oh, well. I bought a second set of towels to embellish and those will be done right! If I can ever locate taupe colored rick-rack…..