PhotoKey exports to JPEG, PNG or TIFF image formats. All of them are compatible with Photoshop. I'm guessing you haven't exported yet, and are perhaps trying to open the PhotoKey project file in Photoshop?
Exporting an image is as simple as selecting the format options you want, in the Batch Export toolset (Batch Export in PhotoKey 3 Pro), then clicking the Canvas Export button in the top left toolbar, or selecting Canvas Export from the File Menu. In PhotoKey 3 Pro you can also use the batch export to export a number of images at once.
If you purchase the Photoshop plug-in version of PhotoKey 3
, you can use it as a plugin from within Photoshop.
If you continue to have trouble, please let us know, as we should have something available quite soon to help make the process clearer.