Peggy's Stretchy Bind-off for Toe-Up Socks
If you are knitting a K1, P1
ribbing, on the row before the bind-off row: K1, M1 ("make one" by
making a half-hitch loop, not by picking up the in-between thread), pull the M1
Repeat around. Bind off row (go up a needle size or two): K1, slip the M1, pass the K1 over the slipped M1, P1, pass the slipped M1 over the P1, K1, pass the P1 over, etc. as for a regular bind off.
If you are knitting a K2, P2 ribbing, on the row before the bind-off row: K2, M1, P2, M1.
Repeat around. Do a regular bind off, as above, remembering to slip the M1 rather than knitting it. The M1 is never actually knit, so it doesn't make a stitch which will add bulk to the top of your cuff; it simply creates an extra loop in your chain bind off.