Hi,
Please refer the SAP note 323736. It does state about the restriction on fonts that the report RSTXPDF4 has. Below is the point to look out for in the note.
Character set/Native Language Support: PDF conversion of non-Latin-1 character sets may require the installation of fonts in order to correctly reproduce special characters, see the following notes:
141343 Latin-2 (for example Polish, Hungarian)
144718 CJK (Chinese, Japanese, Korean)
322998 Cyrillic (for example Russian)
339832 Thai
372666 Greek
625818 Turkish
656088 Hebrew
786734 Latin-4 (for example Estonian, Latvian, Lithuanian)
940025 Arabic
Cheers,
Arindam