Mini-HowTo submit RMarkdown articles to ArXiV
ArXiV is a place for publishing scientific technical reports and drafts which is tightly tied to LaTeX. That is why if you generate a PDF from your RMarkdown article it will tell you, hey, this has been generated using LaTeX, I want the LaTeX source. In principle, RStudio does not admit LaTeX as a final format, only .doc, .pdf or HTML. But it is no big deal.
You only need to add this to the metadata in the RMarkdown document
output: pdf_document: keep_tex: true