A kicking strap (known as a vang in American English) is not used on a Hobie 14.
You can use one, but as Matt M. said, it's more trouble than it's worth. It gets in the way, and there's no real benefit to it.
Racers use the fitting on the boom to rig a shock cord preventer that has a hook on the free end. Sailing downwind, the hook is clipped in to the forward trampoline track near the corner casting, keeping the boom out to one side in light air.
Class rules prohibit attaching the preventer to both sides of the boat at the same time (like on a bridle), so it has to be unclipped / reclipped in order to gybe. An unplanned gybe is a very bad thing, which usually results in a high-velocity hook when the shock cord breaks.
The preventer is stowed most of the time - the hook is clipped into a loop of line at the gooseneck.
You can see one in use here (barely) - it's the blue line leading from the boom to the front corner: