I take it you mean a heat plate that goes on the heat stove on the intake when you put headers on, correct? If so, you use a gasket, no RTV. RTV will simply burn out, causing a leak.
Something that I wondering about, you mention in your post that you bought the part from this site? AFAIK, the site does not sell parts, other than the occasional license plate topper. I'm inclined to think you might be confusing this site with
Langdon's Stovebolt , which is understandable given the similarity in the names.
