Another option for you is the Suunto clipper. Its a small compass that can clip to a watch or shirt etc.

I have a couple of the small Silva (brunton) button compasses stashed in kits, but I changed my EDC compass from the Silva watch band compass to a Suunto clipper and have it clipped to my pocket. But it might be small enough to fit in a PSK for you.
Its a 15mm compass in a 25mm bezel, but the clip extends an extra 5mm on one side. Its about 9mm thick. Sorry about the millimeters, but 25.4 mm is equal to 1 inch. (if that helps)

http://www.suunto.com/suunto/main/index.jsp Then go to the products drop box and select all products, then Field Compasses