Currently there are 12 native Telephoto Prime lenses for Pentax KP and 7 of these lenses are autofocus (AF) type.
KP also has a sensor based image stabilization system which means that all of these lenses will be stabilized when used on KP.
Since Pentax KP has environmental sealings (Weather Sealing), you may like to couple your camera with one of these 2 Telephoto Prime lenses with Weather Sealings.