Hatch offset

What type of router bit is used to cut the offset for the galley hatch??? I used a plastic hinge with no offset and(of course) the hatch doesn't close fuuly at the bottom....in hind site I should have spaced the leading edge of the hinge an 1/8" to allow for this....I'd like a nice clean, uniform cut so haw does this work
Thanks,,,,TC

Thanks,,,,TC