I use that little case for my Nikon Coolpix s8400 which closes up nice and flat. I bought a Sony NEX-5 and had to get a larger case. Your camera appears to be about the same size as my NEX-5 which would mean it is probably too thick to fit that case. You might need to buy a case that is a little thicker to accommodate the thicker camera.
The RX100 has a slightly loose fit in the case. Just by itself, the camera will bounce around a bit. However, there is plenty of room for a extra battery, memory card and narrow neck strap. With a neck strap attached it's almost a perfect fit.