Cannot tie traits in homebrew Barbarian Subclass to Rage Activation,

I am trying to make a subclass similar to the Totem Barbarian with options, but I am unable to tie the selection of a trait to Activate Rage. I even tried creating a subclass based on the Berserker Barbarian subclass and just renaming it to use the activate rage feature, but the feature then disappeared. The only options I can tie a trait to are options from my other traits, Rage is not an option. 

I tried to find another thread discussing this but didn't find any, so I think I'm just missing something.

Thank you