My 2011 Agile has factory wire looms running behind the overhead cabinets, it is nearly impossible to fish new wires in that area. I have successfully run wires behind the window top trim panels and the side panels.
If you are trying to install new dash radio rear speakers and your RT has the factory rear surround speakers with the auxiliary rotary switch selector to switch between surround and dash radio outputs, you can tap or use the existing wires for the new rear speakers…assuming that is what you are trying to do.