Your local dealer should have one. There are not really that many different ones for a particular year / model.
These keys are basic keys, nothing to "program" but they do need to be "cut" to fit the tumblers. Normally they come precut for the few different combinations.
Programming refers to those keys with a IC in them. We are not there yet with Kubota tractors... give it a few years and I am sure we will have smart keys.
David