errata from designer:

RT - right twist, K2 tog, leaving sts on left hand needle, then insert right hand needle from the front between the two sts just knitted together, and knit the first st again, then slip both sts from needle together.

LT - left twist, with right hand needle behind left hand needle, skip one st and knit the second st in back loop, then insert right hand needle into the backs of both sts and k2tog-b, then slip both sts from needle.