In this picture, I have already begun to pull the running stitches taut. I created a series of concentric circles on a diagonal fold (see the 'scalloped' area to the left). Then I stitched rows of running stitches from the side of the shirt to the circles.
This is the sleeve on the other side, before I pulled the stitches to gather them.
We've had rain all day today, and by the time I dyed and washed the shirt, it was too dark to take pictures. So I will try to get some taken tomorrow and post them.