Errata:

Replace the Gusset section with the following
Gusset:
Needle 1: Knit across (Instep Stitches)
Needle 2: K1, Kfb, K16, Kfb, K1 (Heal stitches)
Repeat this 5 more times, knitting across needle 1 & increasing 1 stitch at each end of Needle 2. 6 rounds total. 20 instep stitches & 32 instep stitches.