Couple of weeks ago we were working on Kote Hineri; I am at least a foot taller than my daughter. My hands are correspondingly larger; I haven't measured, but my palm is probably an inch wider than hers. How can she apply Kote Hineri against me (or other larger people)?
Ignore for a moment that this will never be her "goto technique" against large people; she is perfectly capable of using her lower center of gravity and superior skill at blending to introduce me to the mat at high velocity. We accept that, but when studying kata, we try to learn how to do the technique realistically, effectively, and correctly.
Dogmatically speaking, Kote Hineri should be performed with the middle finger across uke's knuckle, and the thumb in the "pocket" of the palm. It is extremely difficult for someone with a small hand to perform that against someone with a large hand.
One option is to slip the hand down and work against the fingers, rather than against the hand. I am skeptical that this provides the same degree of control. The goal of a joint lock is to use the joints to communicate the control/hold to the whole body and to effect an unbalance. Working against the fingers is likely to break the fingers; at that point the control is based on pain and fear rather than on full control.
A second option is to use the other hand to reinforce; in many kata this is a legitimate option, but in Go Shin Ho No Kata, the other hand is used to capitalize on the unbalance.
Other suggestions? How do people accomodate different body sizes when doing joint locks? (I think the general question is interesting, but I think I'll limit this question to joint locks. If you think that the kote hineri is different from other joint locks, explain why.)