Zoom to Fit shortcut

Glad it all worked out.

Thank God and the wisdom of allmight engineers. 
Shift + /

It's called Fit. It's in the keyboad shortcut list in the Panels>Composition Panel section.

Zoom Out: , (comma)

Zoom In: . (period)

100%: /

Fit: Shift + /

Fit up to: opt + /

Unless there is a different keyboard shortcut you are talking about?

like Shift+/ ?