Hi Glocke.
I too purchased the kc-130,but i already had the c-130 pro and c-130j addon,so i dont know if you have the 2d panel,i know you need the c-130 base or c-130 pro,in order to get full functionality of the aircraft plus the vc cockpit,but in the 2d flight deck,you should have a panel of symbols in the lower left corner,if you do,then click on the hose symbol to bring up the refuel panel,its just above the blank symbol,i think is about the 3 one up from the bottom,on the right.
regards alan. 8-)