The .PDF connector has been added into robotic studio as of version 8.0.1027. If you have an earlier version I recommend upgrading. If you are planning on using it at all I recommend upgrading to the newest version, additional .pdf support has been included in version 1030.
Additionally, it is not a default tool for robotic studio. In order to find it you will have to go to the 'Tools' tab at the top of the screen (File, Edit, View, Debug, TOOLS, Window, Help). Click it and select Choose Tools. From there filter via the words '.pdf' and it should show up. Check the box for the tool and it will now show up in your toolbar.