title: Code chunk font size in Rmarkdown with knitr and latex
body: <p>In knitr, the size option works fine in a <code>.Rnw</code> file, the following code generates:</p>
  
  <pre><code>\documentclass{article}
  
  \begin{document}
  
  &lt;&lt;chunk1, size="huge"&gt;&gt;=
  summary(mtcars)
  @
  
  
  \end{document}
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/2iZ4I.png" alt="rnw"></p>
  
  <p>However, I can't get it to work in Rmarkdown. The following code does not change the font size, as it did in <code>.rnw</code> file. The same thing happens when trying to set options with <code>opts_chunk$set(size="huge")</code>.</p>
  
  <p>Is this the expected behavior? How does one change the chunk code font size? (I mean using knitr options, not by adding <code>\huge</code> before the code)</p>
  
  <pre><code>---
  title: "Untitled"
  output: pdf_document
  ---
  
  ```{r, size="huge"}
  summary(mtcars)
  ```
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/bHgr0.png" alt="enter image description here"></p>
  
  <p>I am using RStudio Version 0.98.987, knitr 1.6 and rmarkdown 0.2.68.</p>