Thanks for replying Nik. This is my problem…I stitched 2 vertical images to make a panorama and it ended up suiting a square format/crop. I want to get a 20″x20″print made by a local print shop so I needed a 20×20 cropped image. I was able to get the crop I needed in ACDsee for Macs.
If you want a literal crop to inches, then there are two ways:
Enter a large pixel value (6000 x 6000) for example which would be 20×20 at 300 dpi
Or, use a square crop and then export at a custom size, which is actually the same thing.