Generating Atom feed with jekyll-feed plugin


I use Jekyll Now template and host it on Github Pages to run my blog. [To be included in R-bloggers] I need to create an Atom (RSS) feed.

I found that there is a plugin for that, which is supposed to work for Github Pages. I tried to simply include it to _config.yml file in gems section. I did not work (meaning no feed.xml file was generated). I thought it might be due to a new version of Jekyll and change gems to plugins, but the file was still not generated.

What am I missing?