K1 p1 rib for 10 rows.

Leg: 30 rows

Reinforced heel flap on needles 1 and 2:
Row 1: k1 sl1
Row 2: sl1 p across

Pick up 17 stitches for instep

Set up row: k2 tog at end od needle 1 and ssk at beginning of needle 4.

Decrease instep over next 22 rows.

Foot: slip last stitch on needle 1 and first stitch on needle 4 on odd rows.