how to use latex in r markdown code example

Example 1: markdown in latex

% In your preamble
 
\usepackage[smartEllipses]{markdown}

% In the main body of your document

\markdownInput{example.md}

Example 2: markdown in latex

% In your preamble

\usepackage[inlineFootnotes]{markdown}

% In the main body of your document

\begin{markdown}
Here's a link to [a website](http://foo.bar).  And now^[with `markdown` v2.4] you can also use inlined footnotes with `inlineFootnotes`.
\end{markdown}