Picture frame with round corners

Hi all,
I’m doing a refactoring of my photo web site and again need your help.

To make the web site look & feel consistent, I want to automatically add, when a photo is getting displayed, a frame around it. I want this frame with round corners, and if possible, with round corners inside the frame.

I’ve tried to create a movie clip with this frame, and to resize this movie clip to fit the photo size but the problem is the frame thickness is not consistent from a photo to another as the “resize” operation changes this thickness.

Any idea how I can achieve this effect?

Many thanks again for your help.