The Sony RX-100 should be supported by Aperture 3.4.3 - it has been introduced with Raw Compatibility update 4.01 for Lion and Mt. Lion, see:
In what way are the raw files not recognized? Can you not import them or not open files that you already imported? is it only aperture that cannot open the files, or also iPhoto?
Did the insatllation of the Compatibility Updates 4.01 really succeed and is your profile signature "Mac OS X (10.7.5)" correct? On some Macs this update failed to instll, because the system had the wrong build number, then it helped to patch the build number: see Re: digital camera raw compatibility update
Thanks, Léonie, for trying to help.
The already imported files don't open.
Didn't open, I have to say: Now I see, I have to click on every single file and wait until it is transformed.
I am probably too impatient and Aperture is too slow. (As a professional photographer I would become crazy at that speed....)
Thanks anyway. It was good to learn that somebody cares in that community!