First I crocheted the leg section using a ribbed stitch. Then I folded it in half and used sc to join the two edges. For the foot section, I'm using two strands of yarn held together. I started with a chain the length of the top of the foot. Then, sc across the chain, and around the bottom of the leg section. I used sc across the back of the chain, ch 1, turn, and worked sc back along the row and cont around the leg, and back up the side.
So, its worked in rows, not rounds. I'll repost with the completed bootie so you can see how it worked out.