'Jump to label' is a command used in eventing to skip half of an event until the 'label' is reached. It doesn't have anything to do with the player's movement.
What you should do is create an event at the riverside which, when confirmed makes the player jump across using a movement event.
Then you simply have to press 'Through ON' (or whatever it's called, I can never remember :P) and input the jump movements for your character to reach rocks etc.
At the end of the event be sure to turn 'Through OFF' or your character will be able to walk through everything.