At the moment we dont support the ability to render the HTML but it is something that has come up before. One of the teams we're speaking to wants to classify blog posts and would like to be able to preserve their formatting. If this is something that's important to you we would consider adding it so maybe drop me an email at raza[at]humanloop.com and we can discuss?
Congrats on the launch! Would Humanloop be able to support HTML files or URLs? A client of ours has a need to annotate verbose web pages.