Mark, this one from your site is really very similar to Charles':
http://dharesearch.bowditch.us/0071.htm
Charles, in many ways, my attributing your sword to the Ratanakosin era really isn't much more than saying "this one looks like it's from the late 18th to 19th century". It's hard for me to more definitely opine on age without handling it, as this may very well be a later sword in an earlier style (but I don't think so).
In that regard, I lean towards Ratanakosin (in style anyway) as some of the themes on the fittings evoke what I think of as an evolution of some elements well-established as Ayutthaya. I'm specifically thinking about the stylized lotus flower-petal themes on your sword's scabbard fittings and handle towards the blade (I'd love to see some close-ups of these elements, if you have the time).
The lotus bud pommel is, as Mark points out, not as helpful an identifying feature as we once thought as it appears in various forms on swords from many different times and places.
In any event, one reason I wanted to wait is because we've recently been fortunate to have some new Thai members who have been very helpful, and I'm hopeful they'll come forward with some information. (PUFF, are you out there?
).