I’m still using Rapidblog. Just post on Blogger and the posts show up on my Rapidweaver Blog. Only issue at the moment is that the posts do not show up in the RW preview.
RWBlog relies on libraries built for php v5. High Sierra comes with php v7 so preview no longer works, I’m afraid.
Someday we may rewrite RapidBlog or a similar plugin like it – but it will have to be a substantial reinvestment of time, money, and priorities. Unfortunately YourHead operates on a pretty slim budget. (in other words, i’m too broke to do the work, sorry guys. 
)
Until then RapidBlog is in limbo. It continues to function as normal when published to a server that supports php v5 – but cannot preview.
Perhaps Yourhead is willing to hand the source code of RapidBlog over to me.
I’m afraid I’m not able to. Although I own the code and plugin now, one of the contractual agreements I made with LogHound when taking things over was not to publish the code or disclose in any way.
I will point out, however, that all of the current issues are with the PHP libraries (relying on an old version of Pear). They are not closed and are exported verbatim. An enterprising developer could probably replace the requisite libraries and get things working again.
If someone would like to do this dev work, I’d be happy to revenue share the resulting sales (don’t get your hopes up – RB doesn’t generate very much revenue currently).
Isaiah