Below you can see the front-view size comparison of the Ricoh GXR S10 24-72mm and Pentax K-S2. The Ricoh GXR S10 24-72mm is clearly the smaller of the two cameras. Its body is 9mm narrower, 21 mm shorter and 29 mm thinner than the Pentax K-S2.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.