For Windows 8.0/8.1 RT, another jailbreak exists thanks to Myriachan from XDA. You can find this jailbreak in the repo, or you can find on XDA -- http://forum.
To jailbreak your Windows RT device, just follow the instructions in the thread -- download the .zip file, extract it, and double-click the runExploit.bat file.
Download the jailbreak tool specific to Windows RT 8.1 from a reliable source. Disable any antivirus software temporarily. Run the jailbreak tool and follow ...
An all-in-on package for Tegra based Windows RT tablets (ASUS VivoTab RT, Lenovo IdeaPad Yoga 11, Microsoft Surface RT & Microsoft Surface 2) Extract · Disabling Secure Boot · Windows Configuration · Jailbreak Killing Updates
I made this guide with my experience on jailbreaking the surface rt, 1 and 2 (i have a lot of them, lol) and i hope this helps someone jailbreaking theirs.
This tool will sign every exe and dll files in all sub folders if you select Sign folder! Best of all: It also runs on Windows RT directly :) Have fun!