Help Creating Frame/Border (Action)

I would like to make an action that creates a frame around a picture. I know how to make an action, and I know how to make a frame. The problem arises because I would like to make sure that the border around the photo is the same size all the way around.

So, if I wanted to make a border that is 10% of the width of the picture, how do I do that? If I type in 10% for both the width and the height in the "canvas size" folder, then the border will not be the same size around the photo.

So basically, I want to make an action that I can use for ANY sized photo (any aspect ration) and it will always make a border that is a specified percentage of either the height or the width.

Any ideas?

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Miguel