Order of sentence and using 's

...absolutely 100% our doing, not the Restaurant's.

or

...absolutely 100% our doing, not the Restaurants.

The first one feels right, but looks a little odd.

I think it's the first, because you would say

...the Restaurant's doing.

even thought it might not look right. And, I think you have to show possession, right?

Can someone clarify, and hopefully point me to a resource?

Solution 1:

...absolutely 100% our doing, not the Restaurant's.

or

...absolutely 100% our doing, not the Restaurants.

The first one feels right, but looks a little odd.

It doesn't look in the slightest bit odd to me. The only odd thing there is the capital letter in Restaurant. Anyway, the top one is the correct answer.

Can someone clarify, and hopefully point me to a resource?

Gosh, I don't have any resources except my own wild guesses.