Alright, I figured it out. There are two ways of going about this:

1) "If you are using a MacBook, to use a function key, you must press the fn key (the lower left key on the keyboard) at the same time", so it is not just Cmd-F9, but Cmd-fn-F9. Which produces the braces at insertion point, in which I can just type.

2) The Insert > Field... *does* work, but I have to do this several times, in effect, nesting each field... one of which is the REF field, which I do each time for each dropdown.

Thanks!!!