I'd been stitching 1/4 inch from ditch - using the edge of my foot as a guide - I liked that better than aiming at the ditch, but MUCH prefer this!
I guess that stitch is called a scallop - didn't look in my manual to see. I set my machine to "3". Smaller than that and it's almost a zigzag, but with rounded edges. I'm happy with that, but the baby quilt I was looking at the scallops were much wider than mine.