I have medium sized hands, and the nude Sony RX100 wasn't very comfortable to use. Two accessories have changed things dramatically for the better.
The first is Richard Franiec's grip. [Disclosure: Richard gave me a review unit to keep]. I had serious concerns about this grip spoiling the minimalistic beauty of the RX100, but having now applied it, I have to say that the combination remains very attractive. The finished texture of the Franiec grip is nicely matched to that of the RX100, and the overall look remains clean. More importantly I cannot overstate the improvement to the handling, while the size and weight of the camera are - for all practical purposes - unchanged.
The Franiec grip costs $34.95 plus shipping and was well worth the price, but there's a second accessory which has had an equally significant impact when it comes to improving the handling of my RX100. That would be the little red stick-on Gariz soft release button.
I use these soft release buttons on virtually all my Micro 4/3 and smaller cameras. Not only do they allow me to handhold more comfortably; they also help me to avoid camera shake as I trigger the shutter. This picture shows how it works in practice:
As you can see, I use the inside of my first knuckle to squeeze down the soft release. Much more comfortable and natural than curling my finger to push the shutter release button with the fingertip.
The Gariz buttons adhere using 3M double sided tape, and I've found the attachment to be very secure. A pair of them (black and red) will set you back about $12.
A few additional views: