I’ve had it installed for quite a while so maybe something broke recently. I did find this on the plugin’s issues list on GitHub. Instead of clicking OK, click Apply and then Cancel when mapping the paths…then it should let you pick the SDK from the dropdown.
Also if you started IntelliJ in the project directory and are using Rubymine or one of the other “small IDE’s”, delete the .idea directory from the project and retry in the small IDE. Sometimes the full Intellij puts things in that are not compatible with the small IDE’s like RubyMine.
