You should read the page I can't find file `Helvetica'

If you use the Knoppix 7.2.0 DVD you can try the following commands in an LXTerminal.
Code:
mkdir -p /home/knoppix/git
cd /home/knoppix/git
GIT_SSL_NO_VERIFY=true git clone https://github.com/progit/progit.git
cd progit
sudo apt-get update
sudo apt-get install -t unstable pandoc
sudo apt-get install ruby-rdiscount rubygems calibre
leafpad latex/config.yml
Use existing fonts:
Code:
font: TeXGyreHeros Regular
bold: TeXGyreHeros Bold
mono: DejaVuSansMono
Save the file and exit leafpad. Now you should be ready to create the PDF file.
Code:
./makepdfs en
Of course, you can use other fonts, but they must be installed on your system.