We are trying this on 4.1.4 and on 4.2 BETA. The PDFserver machine is running 4.1.4 and both the 4.1.4 and 4.2 machines are trying to pull PDF's from the 4.1.4 machine. Certs are our own, but are based on hostname, whereas the PDFserver looks for IP.
Can you supply some information on which version of Splunk you're using, which version of the pdf app and what errors you're receiving? Also are you using a Splunk-generated SSL certificate or are you supplying your own?