The RX 100 Mark 2 is not (yet) supported - the camera is rather new and isdifferent from the predecessor model.
You'll have to wait a bit for the release of the raw support.
As Leonie says. I expect (just me personally -- I use Sony cameras and am attentive to their support) that we won't have too long to wait for an Apple Digital Camera RAW Update that includes the Sony RX100M2 and the RX1R.
Record RAW-JPEG pairs for the time being, and then process the RAWs when the update comes along.
Adobe's DNG converter is easy to use. I have used it for raw files of my Lumix.
It is free, so you could download it and give it a try.
The dng's from DNG converter are supposed to be supported by Aperture:
Aperture works with most DNG files generated from cameras that support this format and with DNG files generated by the Adobe DNG Converter with the “Convert to Linear Image” option turned off.
Only I am no longer quite convinced. I used to be able to import dngs created by Adobe's DNG converter, but since the upgrade to MacOS X 10.8.4 does Aperture no longer accept newly created dngs.
But any software that will convert the raw to tiff will do - the software that comes with the camera or Photoshop, for example.
Thank you Leonie and Kirby. In the meantime, can I use a ARW to DNG converter to view the pics in Aperture? Any recommended converters? Adobe's seems user friendly.
This is what I am doing: recording RAW+JPG, importing, and using the JPGs to confirm the data in the RAW files (which are currently not available in Aperture). And waiting for the Apple Digital Camera RAW Update (again -- I make no promise this will ever appear). For me, it is not worth the work-around as long as Aperture will be able to process the new RAW formats within a few weeks. Obviously, your situation will require its own response.
The safest way to proceed now, if you need the RAW files now, is to use the Sony-supplied RAW converter and convert your ARW files to TIFF. The most recent version of Sony's RAW converter is 4.2.02. You can download it here.