You're only out of luck if you want to install any software on it as it is designed to run only the apps that are already on it:
Windows RT 8.1: FAQ
Windows RT 8.1 is a Windows-based operating system that's optimized for thin and light PCs that have extended battery life and are designed for life on the go. Windows RT 8.1 only runs built-in apps or apps that you download from the Windows Store. Windows Update automatically keeps your PC up to date and Windows Defender provides up-to-date virus and malware protection.
It's mostly designed for email and browsing and it is great for that purpose. There are also some apps that you can get at the Windows Store that will run on Windows RT. My software is far too complex to run on the Windows RT system.
If I ever get the chance to write a browser-based version of the software, that would run on the RT, but it wouldn't have very many features.
Lloyd