Now it works great! Thanks OP!!
I had some trouble getting it working. So I made some changes to the plugins code that is shared from my GitHub
https://github.com/gregruthenbeck/discourse-rss-poster
It’s only been tested against the latest beta version 2.3.0.beta9 +552
It now produces nicely formatted posts automatically (I’m using it to create posts from RSS feeds from StackOverflow, Reddit, and GoogleAlerts).