How to make a black border around a transparent image

[Kris5E39]

I am trying to put a black border around a transparent image and having a hard time doing so.  I have tried doing the canvas size and the only way I can get that to work is if I flatten the image which then I lose the transparency.  I tried another option and also had no luck, can anyone show me how to do this?

[Leslie Moak Murray]

New Layer/Stroke black around the edges to desired thickness/Save as .png.  Do not flatten.

[Michael Bullo]

1. Draw whatever you want on a layer or even fill the entire layer.
2. Apply a Stroke Layer Style.
3. Set the Fill Opacity of the layer to 0%. Leave the regular layer Opacity at 100%.