Keyes is in the movie. Off the top of my head, I can't think of a scene where he's prominent, but once I see the movie again, I'll let you know where to look.
Incidentally, for years 1776 was only broadcast in an edited form (with most of Virginia Vestoff's scenes, as well as the "Cool, Considerate Men" number cut). It's possible that New Hampshire was also edited out of this version; if so, and that was the only form of the movie you've seen, then you would have missed him. Fortunately, 1776 is available complete and uncut on DVD.
ProfStokes