Need Help Streaming with OBS

So I have a Mac and I'm trying to stream to twitch with OBS. When I go to add a source and I select Window Capture, the drop down box where it says Window, doesn't give me the option for the League of Legends screen at all. And when I do get a capture of like Firefox or something, it shows in a really zoomed in version of my capture if I try Display Capture. Please help!