Does anyone know of any remote/cable shutter release that is compatible with the x100s?
I've been looking and I'm not sure if the RR-80 or 90 works.
It sounds like your options are limited with the X100S.
For example, this post suggests that the X100S is not RR-80 compatible, and that your only option is a mechanical cable release.
There is some speculation on the web about X100S having the ability to release the shutter through a mic input.
This user seems to believe that the RR-90 Remote Release does not have the correct USB size for the X100S, but has suggested an adapter for that USB port may work.
To be safe, I would purchase a mechanical shutter release. Something like this.