It doesn’t seem possible to post anything other than plain text into the blog part of Rapidweaver.
I’ve tried pasting markup, but that doesn’t work.
I’ve tried posting HTML directly from Typed, but that results in weird line spacing issues (like really big ones between numbered items in the theme I’m using).
And if you select paste and match style it gets rid of all the bold and italics.
I don’t really want to write my blog posts in the Rapidweaver text box as I’d prefer to use Typed, Scrivener, or anything that lets me write in full screen, and preferably I’d prefer to use markup. I would have though that Rapidweaver would allow markup in blog posts 
Any advice would be great as at the moment I’m having to paste in as text and then try to remember any formating I did such as italics, bold, numbered lists, bullets, etc.