Picot edge cast off
cast off two sts kwise (see Step 1 of Casting off in pattern). Now turn your work and use the cable method to cast on two extra stitches.
turn the work again and with the yarn at the front, cast off two of the three sts on your RH needle by passing them over the nearest st and off the end of the needle.
rep Steps 1 and 2 to end and fasten off.