Almost certainly Duncan Hinds didn't make that food cutter, but had it made for them by a manufacturing concern. In that case, the feet are probably generic and you should be able to get them from any large mechanical component supply house.

Ried Tool & Die has since changed it's name to Essentra Components, and I would get on their web site and search for feet that would fit:

Global Manufacturer & Distributor of Component Solutions | Essentra Components

Snoop around on this page and see if you find something similar to what you need:

Feet, Casters & Glides