You can create PDF report directly from the tool.
Generate historical report and on the top right corner click on the PDF icon which converts all graphs into 1 PDF file.
If you are on Virtual Appliance
then just use it, nothing is required, everything is already installed.
In any other case you will have to install a Perl module to make it work.
You will be prompted for its install when you click on the PDF report.
Installation of PDF prerequisites
It uses A4 format as default. If you wish to change format to "letter" usually used in the US then change parametr PDF_PAGE_SIZE in stor2rrd.cfg
$ cd /home/stor2rrd/stor2rrd
$ vi etc/stor2rrd.cfg