They listed specific instructions in the directions for the small doll.
Divide into two legs as foll: K5, join 2nd ball of yarn and k5. Cont working both
sides at once with separate yarns as foll: Row 32 Inc 1 p st, work to last 2 sts on first half, p2tog; on 2nd half, p2tog, work to last st, inc 1 p st in last st
It's basically the same technique as 2-at-a-time sleeves or magic loop.