I can confirm that PDF files should appear in the news stream. A couple of areas worth checking to ensure the stream is set up correctly; ensure the place where the file was being created is the source for that particular news stream.
The other tool that can be helpful for when content is not displaying in the stream is in the Admin Console > System > Settings > News - This will allow you to rebuild specific news streams.
If the issue continues to persists after these two things, I would recommend creating a case in your Private support group. This will allow our support team to review you specific environment and further investigate it.
Hope this helps.
Thanks for the reply John.
I've done the rebuild so we'll see the next time our MD does an update. Is it worth opening this in the support forum, do you think?