I had similar problem, which i overcame like this:
I put .ttf file into the application deployment and then in then called something like this:
Font font = new Font(28,"VERDANA_MEDIUM", "c:\app\yourFont.ttf",Font.PDF_ENCODING_Identity_H_Unicode_with_horizontal_writing,true);
if you dont know where the deployment is being made (you dont know the real path to your application) and you are running dynamicJasper from servlet, you can get the right path with something like this:
YourServlet.getRealPath("yourFont.ttf") or YourServlet.getServletPath("yourFont.ttf"), dont know exactly:)
Hope this helps...