Thanks to Jean, a.k.a. "jano", there is now a nasal script included in DavePack that allows JSBSim models to properly refuel. All the F-4 models have been updated to use this. I also moved the upper mirror in each F-4, flipping it to a stowed position, to give a better forward view. In order to refuel the following conditions must be met:
1) The refueling system must be activated, and the probe (or door) must be in the extended (or open) position.
2) You must be refueling from a tanker which has a matching type of connection; either "probe" or "boom" type.
3) You must be in "the box" behind the tanker.
When conditions are met you will start taking on fuel, and a small green light will illuminate on the fuel gauge. Fuel will go in to all tanks at an equal rate. If the fuel gauge only shows tank quantity, then the tank quantity will increase slowly until the other tanks are full.
The download rate is 6000 lb/min, which is hard-coded in JSBSim.