I used the tubular cast-on from Nancy Wiseman’s Knitter’s Book of Finishing Techniques. It was a little tricky to do in the round but turned out nicely for the sock. I only wish it were a little stretchier; it’s not quite stretchy enough for the top of the sock.

The needed stitch count is 68, so I crochet cast on 35 (68/2 + 1) and knit the first and last stitches together so the first row has purl bars all the way around (no gap at the start of the first row). Knit three rows; on the fourth row, work K1 P1 ribbing and pick up the purl bars from the first row for the purl stitches. I counted that as my first row of ribbing for the pattern.