If you want a perfect match call the service desk at an established lumber yard (NOT a "big-box" like HD) and ask for the name of the nearest "custom millwork" shop. (If you happen to live in Chicago, I use Skokie Millwork, 847-673-7868)
If they give you the name of a "custom cabinet" shop instead, that shop will likely know who does millwork
When you find them, hanging on their wall will be *hundreds* - perhaps thousands - of custom shaper knives they have made over the years, likely one will be very close to your profile.
They will charge your a setup fee, maybe an minumum job fee, and materials, and run a few feet if you need it or ten-thousand feet if you want it - and if you want to pay a additional fee, they will custom grind a knife from a sample of your molding.
Michael Thomas Paragon Home Inspection, LLC Chicago, IL mdt@paragoninspectsDOTcom
847-475-5668