Thanks for reaching out to us! Yes, thanks to a recent enhancement there is a simple way to do this:
– If editing a Photo, within the Basic tab > Crop tool, choose “Custom Ratio…” in the dropdown and enter 5.25 x 7.25. You can then crop to this exact dimension.
– If creating a Grid Collage or starting with a Blank Canvas, do the exact same thing in the Constraints dropdown.
Let us know if you have any questions.
Regards – The Ribbet Team