You can now customize your PDF exports in a few ways. You can configure Portrait or Landscape, margins, and a general font size adjustment.
To customize these settings, you’ll want to click on your user name in the upper right and go to Account Settings. From here, go to PDF under Export. Here, you can set the various settings listed above. Font Adjustment is a 0-1 value you can alter to explicitly set the scaling used in going from normal font to PDF fonts. For example, a value of .5 will use PDF fonts at half the size of the fonts used in your normal dashboards. You should find these values enabling you to render much better looking dashboards.