Of all the movie paper to be considered rare, this is the absolute last thing I would have predicted. This is the domestic herald from the 1951 RKO release. This is something that would have been ordered by a theatre owner and handed out in the weeks prior to the film being show at a specific theatre.
In all the years I've been collecting this is the only one I've ever seen. I've seen three six-sheets over the years, but just one herald. How weird is that?! Perhaps I just haven't been looking in the right places, but you'd think something like this would not be that hard to come by. They must have been printed by the thousands, and were made to be given away. It really is a nothing little thing, just a single sheet folded, one color printing (magenta on the front cover, blue on the inside). Cover art is the same as the A-style half-sheet (but reversed),
the inside art is the same as the B-style half-sheet and 24-sheet.
The back cover has the date and time for the Paramount Theatre, and advertises that Nature's Half Acre will accompany it.