MacOS Spectator Plugin
This app allows you to spectate games simply by clicking a button in your browser, no terminal required.
Once you have downloaded the app, right click it and select "Open" (you only have to do this once). Don't worry if nothing happens, that's normal.After that, just make sure to click "Open Spectator App" whenever want to spectate a game.
Note: In order for this to work you must have your League of Legends app in the Applications folder.