title: Specifying papersize for md to pdf conversion
body: <p>I've read you can specify papersize by <a href="https://github.com/jgm/pandoc/issues/600" rel="noreferrer"><code>pandoc -V papersize:"a4paper" ...</code></a>.  This doesn't seem to work anymore.  I've managed to specify <code>B5</code> using</p>
  
  <pre><code>pandoc -V papersize:b5 -o out.pdf in.md
  </code></pre>
  
  <p>But this fails for e.g. <code>b6</code>.  The following <code>-V</code> arguments also all appear to have no effect:</p>
  
  <pre><code>-V papersize:b5paper
  -V papersize:"b5paper"
  -V "papersize:b5paper"
  </code></pre>
  
  <p>What is the proper way to format this, or am I missing something more fundamental?  In my opinion <a href="http://pandoc.org/README.html#creating-a-pdf" rel="noreferrer">the documentation</a> is far from clear, lacking e.g. any examples.</p>