Mark Dodd

I"m looking for a way to add a thick border to an image and then add a thin keyline within that border. I've seen the video on how to extend the canvas to add the thick border, but I don't see how to add the keyline within that border area. I've attached a sample of the type of thing I'm looking to do. I've found plenty of tutorials for photoshop, but I'd like to do this in Affinity Photo