title: Changing font in PDF produced by rmarkdown
body: <p>I am producing reports using rmarkdown. When knitting a PDF</p>
  
  <pre><code>---
  title: "Untitled"
  output: pdf_document
  ---
  </code></pre>
  
  <p>I would like to specify the font to be used in creating the PDF. The official <a href="http://rmarkdown.rstudio.com/pdf_document_format.html">documentation</a> (see section "LaTeX Options) says I can do this. 
  <img src="https://i.stack.imgur.com/9kRTk.png" alt="enter image description here">
  However, I've never used LaTeX and fail to understand how such selection can be made in YAML options at the top of the .Rmd document used by <code>rmarkdown</code> package.  </p>
  
  <h2>Question: How do I change the font in the PDF produced by rmarkdown?</h2>
  
  <blockquote>
    <p>sessionInfo()
        R version 3.1.0 (2014-04-10)
        Platform: x86_64-w64-mingw32/x64 (64-bit)</p>
  </blockquote>
  
  <pre><code>locale:
  [1] LC_COLLATE=English_United States.1252  LC_CTYPE=English_United States.1252   
  [3] LC_MONETARY=English_United States.1252 LC_NUMERIC=C                          
  [5] LC_TIME=English_United States.1252    
  
  attached base packages:
  [1] grid      stats     graphics  grDevices utils     datasets  methods   base     
  
  other attached packages:
  [1] ggplot2_1.0.0 RODBC_1.3-10  knitr_1.6     dplyr_0.2
  </code></pre>
  
  <p>I've never used LaTeX and don't want to get into it at this very mom</p>