iFrame in Markdown

I’m a newbie here, interested in using Glitch as a collaborative markdown editor. We want to embed iFrame code in a markdown page, and then be able to see it rendered in the preview. Is this possible? I see it works on an html page, but not markdown. I also see that other html embeds (e.g., and tag) do preview correctly on a markdown page. Thanks for your help!

This is not possible using markdown, you can use the html iframe tag. Some markdown parsers does not render HTML though which can be an issue.