So far as I can see, this camera does not have an analogue video output. Therefore, you will need to adapt the HDMI to analogue.
This is the sort of thing you need: http://www.ebay.co.uk/itm/HDMI-to-Analo ... 1371404382
Personally, I would strap a small camera on and not bother with the output from the RX100. find one with a similar field of view and you should still be able to frame your shots.