resolution half or third for fast render

Heyah,

My question is how do I render an AE composition through AME with resolution set to half or third? In the past this could be done in the 'render settings' menu in AE, but since it now goes through AME, I cannot find it. Even if I put the resolution in AME really small, it always renders the full frames (composition settings is 1080).

How do I change this so I can fast render work in progress?

Thanks!