May I refer you here:
Comprehensive Pentax Flash Guide - Articles and Tips | PentaxForums.com
But you probably want to spend your time shooting pictures not reading. I was recently using a KP with the AF540FGZ-ii and so spent some time looking at this. There are two ways Pentax cameras work with remote flashes; the old fashioned method where the flash from the cameras sets off the remote flash, and the new fangled way where the camera flash emits some preflashes the configure and tell the remote flash when to flash. The old way has the advantage of being compatible with almost every camera and flash made since the 1970s, but does mean the camera flash will contribute light to the scene. The preflash method allows the camera flash to act as a master in which it configures and triggers the remote flash and also contributes illumination, or as a controller in which the preflashs configure and tell the remote flash when to go off, but the camera flash doesn't actually flash while the shutter is open and so does not contribute illumination to the image. The KP is unable to operate in the preflash Master mode, only as a controller for off camera flashes, and so cannot add illumination to the image. So you must be operating in the old style of triggering off camera flash. Set the KP flash mode to Controller. On the AF540FGZ-ii the old versus new remote flash trigger mode is set using the functions. The AF360FGZ-ii might be the same, consult the flash manual.