As I mentioned in the original string, I am reading Kao, for this purpose, as "bump" rather than "shoulder-stroke." The Raise Hands to White Crane transition certainly shows Kao in the upper body, but the energy in the leg is Ji (in fact, because you are twisting, then stepping into an empty step for White Crane -- which could very easily sweep out the opponent's leg -- the whole motion may also be called Lie; shoulder in one direction and the leg in two more).
Kao appears in the legs whenever you shift forward, closing a small distance between your leg and the opponent's leg. It can be demonstrated by the hips in turning steps as well -- just be sure not to allow your hips or butt to protrude. Posture is everything.
The energy of Kao is sudden and explosive (Fa Jing). It is important that you understand how the legs interact in the form manifestations of Kao (including Horse's Mane) by pushing against each other to stabilize the root and brace the shoulder strike. Otherwise, it will be extremely difficult, if not impossible, to use this energy as it is hidden in the steps.