Feathered Images With PaintShop Pro X6
Used the Selection Tool with type "Square" and mode "Replace". Feather was on 5px. After selecting just inside the image I copied the selection to a new image that was the same size and had a transparaent background. The new image had a resolution of 72 px/inch and was a Raster Background.
I used "Paste as New Layer" and then used the export optimizer for .png. I didn't really find help on the web saying to do it this way, but it works.