If you fetched the source directly from phpaga's subversion repository you will need to install the following libraries. (They come already bundled with the official phpaga packages.)
phpaga uses Smarty as its templating engine. Smarty is written by Monte Ohrt and Andrei Zmievski.
The R&OS pdf class is a PHP class that allows the easy creation of PDF files. Get the file named pdfClassesAndFonts_009e.zip which contains the class, sample, and the required font metric files.
http://sourceforge.net/projects/smarty-gettext/
smarty-gettext is a Smarty plugin written by Sagi Bashari that allows to use gettext with Smarty templates.