There is a long-standing bug in the Webkit engine used by this class, which means that sometimes the text in the resulting pdf is rendered poorly when using small font sizes (e.g. <= 9 px). The kerning on some of the characters is wrong.
This can be fixed by forcing the engine to include the font within the generated PDF.
Simply put, include a font within your html to be converted using the font-face CSS rule. E.g.:
<style type='text/css'>
@font-face {
font-family: mysans; src: url('fonts/texgyreheros-regular.otf'); font-weight: normal; font-style: normal;
}
div, td, th {font-family: mysans;}
</style>
(more info:
code.google.com/p/wkhtmltopdf/issue
...
chmielot.blogspot.co.uk/2010/10/fon
...
)