How can I show page numbers (preferably like 4/10, 5/10 etc.) on an rmarkdown beamer presentation?
In the front matter of the document, you can include a .tex file with extra commands as shown in RStudio's documentation here.
I created a new .tex file that I called "header_pagenrs.tex" which only includes the top 2 lines from @user4281727's answer:
\setbeamertemplate{navigation symbols}{}
\setbeamertemplate{footline}[page number]
Then I referenced this file at the top of my .Rmd file:
---
title: "Things and Stuff"
author: "Me"
output:
beamer_presentation:
includes:
in_header: header_pagenrs.tex
---
If this still gives you errors, you might also be missing some required TeX packages (a separate problem from RStudio and rmarkdown).