The cpdf_set_font() function
sets the current font face, font size and encoding. Currently
only the standard postscript fonts are supported.
The last parameter
encoding can take the following values:
"MacRomanEncoding", "MacExpertEncoding", "WinAnsiEncoding",
and "NULL". "NULL" stands for the font's built-in
encoding.
See the ClibPDF Manual for more information, especially
how to support asian fonts.