I've never heard of ProntoUtil. But you can download MakeHex and the MakeHex GUI from the JP1 site where you got RM. Then enter the protocol, device and sub-device from the general tab and the range of OBCs, and MakeHexGUI will generate all the pronto hex. There is another tool called IRPMaster or IRMaster that can be used in a similar way. It's more advanced and can even send the codes if you have Global Cache or other hardware.