Thank you for your input, West. I did find this record in LDS IGI, but it was a member submission. Do you have access to the Chilton PR? Richard consistently stated at census that he was born Chilton, but I do realise, of course, it is possible he was living in Berkshire at the time of his marriage, or, at that period of history, he did not know where he was born, only where he had lived within his memory. It looks as though extended family Chamberlain lived in nearby Ramsbury, Berks.
I believe Chilton Foliat PR do exist for the period, but it appears they have yet to be transcribed. I can only hope that one day either someone does transcribe these records or some kind soul will look up Richard's marriage, prior to 1816 & the christenings of his 4 sons, at the Wiltshire public records office.