No you don't have to create models for each view(.erb). In case you want to add new view to existing model, just add new method(def) into the controller(.rb), and new view(.erb) with the same name as of the new method.
let say there exist a model DemoController.rb in app/Demo. you can add new method to it as like
class DemoController < Rho::RhoController
...
def index
end
def new_method
end
end
To navigate from the index view to the new_method, you can write
<button onclick="location.href='/app/Demo/new_method'">new method</button>
or
<button onclick="location.href='<%= url_for :action => :new_method %>'"
>new method</button>
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