R Markdown is a good tool for document authoring. It can use Latex statement in R Markdwon directory. But when I try to insert a TikZ picture, I am lost about how to add preamble \usepackage{tikz} in it, so compile will fail.
example code:
---
title: "R Markdown with tikz picture"
author: "Me"
date: "January 10, 2015"
output: beamer_presentation
---
## TikZ picture
- Here is a TikZ picutre
\begin{tikzpicture}
\draw (0,0) circle (2cm);
\end{tikzpicture}
Since actually it will generate a latex document, so it's fine to just add it in latex then compile it to pdf, but I wish I can just do it in R Markdown then click the "Knit PDF" button to generate pdf document directly.