OK, I had to delve into the source code of the module to get a handle on it. I copied the first list of values found in the source code and changed the second to last value in the list of values from 10 to 8 like so: 
  my $pdf = new PDF::Labels(
      "8.5:11:0.2:0.5:3:10:2.75:1:0.25:0.15:8:12",
      filename=>'/var/www/vt/files/labels.pdf',
      fontsize=>'8',
  );

[download]

In reply to Re: Need help RTFM: Setting fontsize with PDF::Labels module by nysus
in thread Need help RTFM: Setting fontsize with PDF::Labels module by nysus

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.