rmarkdown not marked as currently.used when only an markdown file is in project

[Michael Beigelmacher]

I'm using packrat with a project using git and git hooks and before getting to any major coding was writing some documentation. In order to preview .md files in RStudio I need rmarkdown installed which is fine, but because I don't yet have any other .R or .Rmd files packrat::status()
says rmarkdown and it's dependencies are not being used. Creating an .Rmd file with the default template for R Notebooks for R Markdown results in marking the packages as being used. While the R Markdown template has a reference to knitr the R Notebook template doesn't reference any libraries.  Is packrat inferring which packages are used based off the extension, and if so could it be possible to include .md files?