The PF-DS1 adapter is specified to work with the Optio S, Optio S4, Optio S4i, Optio S5i, Optio S5z & S6 point-&-shoot digital cameras. However, since it threads directly into the eyecup-side of the XW and XF series 1.25" eyepieces, it seems that the PF-DS1 could be used with any telescope or spotting scope accepting traditional 1.25" eyepieces (provided, of course, you were using that scope with the Pentax XW or XF eyepieces).
To use the PF-DS1, first unscrew the rubber eyecup from the XW or XF eyepiece. There will be an exposed threading which the PF-DS1 will screw into directly, and then you just insert the eyepiece into the spotting scope as you normally would. Next, attach the digital camera and press it against the four rounded protrusions which keep the camera's sensor parallel to the image. You then turn on the camera and adjust the zoom position upon the digital camera to eliminate vignetting and finally you'll focus with the spotting scope itself.
Of course, it is entirely possible that it might work with other digital cameras as well. The key is to determine whether or not the unit would fit into the receptacle for the digital camera. Here's some help: there's approximately 2.4" (62mm) of space between the tripod socket thread and the edge of the receptacle upon its bottom. The maximum depth of the body from the centre of its tripod socket to the front of the main housing (not including the lens protrusions) is but 0.55" (14mm). The height of the body cannot exceed 2.36" (60mm). The hole for the lens is 1.1" (28mm) deep and has a maximum diameter of 1.65" (42mm) and it begins approximately 0.62" (16mm) to the left of the tripod screw.
As with all digiscoping efforts, you'll need a sturdy tripod with a video-type pan/tilt head as well as a cable release or remote control for your camera.
Dimensions (LxWxH): 2.6 x 3.4 x 2.8 (65 x 87 x 70mm)