our configuration is:
Application Version: 7.1
Java Version: 1.7.0_67
Operating System: Windows Server 2012 6.2 (x86)
it sounds like you may have not set the Default Language Font in Admin Console->Configuration->Region as shown in the following image:
Also, I notice your build of Yellowfin 7.1 is very old indeed! There have been many improvements to the PDF export code over the last 2 years (as well as many other features) so please upgrade to the latest build, it is very quick and easy to do and I guarantee you won't regret it!