How to add the same image to multiple files quickly?

I have over 50 photos of my art to which I need to add the same ''For Sale'' image to the upper left hand corner of.

The ''For sale'' image was created by me and is saved as a PSD.

I can't seem to do that with ''process multiple images.'' Is there any other way to do this aside from opening all 50 photos, pasting the ''for sale'' image, placing it where I want it, then saving each one individually?

PSE15 on a MacBook Pro.

Thanks!