ok wow, I totally missed that. So it is a rule for movement using the survival ring. I guess I was wondering if someone had an advantage for having experience riding on a horse, then that would reflect in a technique.
Attacking on horseback is therefore resolved as normal. If the attacker is on horseback and his opponent is not, maybe rule that he cannot attack with melee unless he performs a guard action or can somehow move faster than the horse because of terrain obstacles, etc..