Interestingly the purveyors of Anything and Everything in the World still list our old standby Hermetite Red, with the proviso that it is unavailable for now.
Ever ones to jump in, Hylomar have a product, new to me, Hylotite Red. Apart from the colour you have to play spot the difference to see how it differs from the well established Blue Version.
RTV in a tube has no advantage over good old silicone bathroom sealer, and both are OK in the right place on an engine, but the second time you come to use the RTV in a tube tube, there's a good chance it's gone solid. Using a small amount of silicone to bed rocker gaskets allows you to assemble loosely, let it harden for a couple if days, then tighten down fully. Usually works where other sealers have failed , especially on bruised castings. Gets a bad reputation because folks use too much...a light smear is all you need, and removal is relatively easy.
Swarfy.