Don't fret too much, Burt. We've all made goofs like this. It does, however, underscore the benefit of thinking through procedures in detail - that is, if I follow procedure x, using tool y, and bit z, what will the result be, and where are the possible problem areas that might result.
When in-letting a plate, you can work from the outside inward, or from the inside (the inner edge of the rabbet) outward. When I did my current table, knowing where I sometimes have router-control problems, I decided to work from the outside (where the edge of the plate will fit) inward, using a template and guide bushing. To get a good fit in the corner, depending on the template being used, a bit with the same, or smaller, radius as the corners of the plate is required. Using a smaller bit requires that the template have rounded corners, concentric to the radius of the plate's corners.