They will fit Pentax and Samsung DLRS, Ricoh used the Pentax "K" mount on their 35 MM film cameras. They will have limited functionality, but once you learn HOW to use them, they will work just fine !! One thing to look out for though, is on SOME of the more recent Ricoh lenses there was a small pin that if used on Pentax DSLRs will get stuck in the autofocus hole on the Pentax and Samsung bodies, if there is no pin, no worries !! You can easily remove the pin from what I understand, so that should ease your mind.
Found this on the net:
Incompatibility Warnings:
Avoid Ricoh P-series ("Program") lenses.
You can identify these lenses by a "P" or "(A)P" setting on the aperture ring similar to the A on the A-series Pentax. When the ring is rotated into the "P" (Program) position, it locks in place and you have to depress a small button to get the aperture ring to move again. These lenses have a small ball bearing contact on the rear flange of the lens that will pop right into the hole that holds the AF cam on Pentax autofocus bodies. The result will be that the lens gets locked tight on the body, only halfway mounted.
Early, non-P-Series Ricoh lenses should cause no problem because they have no extra electrical or mechanical contacts.
Avoid third party lenses designed specifically for the program Ricoh cameras.
Beware of third-party lenses designated "KR" or "PK-R" as they are non-Pentax-compatible Ricoh K-mount and can get stuck just like Ricoh lenses. Chinon brand, Albinar, Soligor, Kiron, Tamron, Vivitar and others made such lenses, so when looking at a third party lens, make sure it's for Pentax K-mount and not Ricoh K-mount!
Lenses designated "PK-A/R" are Pentax and Ricoh compatible, and should be safe.
If you get a Ricoh lens jammed on your camera...
If you do get a Ricoh lens stuck on your Pentax camera you can often remove it by inserting a thin feeler gauge between the lens and mount on the lower right-hand side (with the camera pointing towards you) and working it around until you get it between the flange and the offending protrusion. It can take a long time but you will usually (usually!) be able to get the lens off.
Some people are reported to have had success modifying Ricoh lenses by removing the offending protrusion to make them compatible.