Create a new repo on github
Using R studio
File > New Project > Version Control > Git
Paste the repo url from github
Create a new file
File > New > Markdown
Change 'output=html_document' to 'output=github_document'
Knit the document
Using the git window, commit .md (and not the .rmd) file
NOTE:
For rmd scripts with graphs, knitting will produce <filename>.md and <filename>.docs
Include both files in the repo and the .md will pull the graphs from .docs file when rendering