how to embed standard PDF font?

I need to embed ALL fonts in an existing PDF file.

I have tried to use the code snippet which I found at your online documentation via

http://www.aspose.com/docs/display/pdfnet/Embedding+Fonts+in+an+existing+PDF+file

However this logic doesn't work to embed STANDARD pdf fonts like Courier, Helvetica etc.

How can I embed these fonts into an existing PDF file?

When I use other software (like www.pdf24.org) this is working fine, and the recepient is accepting the resulting PDF file. However I need to build an automated solution using the Aspose .net library.

Thanks for your help.