This is really going to be a programming solution and not specifically a Robotics solution (unless of course you can interrogate an application that performs this function).

My suggestion would be to approach it that way and use a script written in C#. I am not sure you can create a PDF without a third-party library though. Thinking outside of the box, I would start with creating a function to create a Word doc (assuming you have access to MS Word) and inserting images from a file into it (search for "C# Word interop" and then whatever terms get you closer). You can then figure out how to convert that document into a PDF. Adobe might also have a tool to do this that you might be able to install and automate, but generally speaking, Adobe's tools are not very interrogate-able, but the tool might work from a command line, so there's that possibility.

I have not had to do anything similar, or I would provide some examples, but sadly, I do not have any to offer.