A 1:100 dilution of Rodinal is barely enough, even for film, without leaving it in the solution for, like, an hour or more.

And film developer used at film-strength dilutions for paper (much stronger than the OP's 1:100) still leaves paper very much under-developed.

I don't know why you want to use film developer for paper negatives, or specifically why Rodinal. If you've chosen Rodinal for its excellent keeping properties in storage as a liquid concentrate, then try the equivalent of Agfa Neutol WA paper developer, it has the same excellent keeping properties of Rodinal and is designed to work with paper as a paper developer.

If you are using film developer to help control contrast, my advice from years of paper negative work is to start with standard paper developer, then fine-tune your process from there. Some people report good results from a split-development regimen of paper and film developer, while others report good results from a highly dilute paper development combined with sitting unagitated in a water bath, and then more developer, gauging the results by inspection. So there's a lot to learn here.

If you are using film developer just because that's all you had on-hand, go get some concentrated liquid paper developer and have another go at it. I loved using Agfa Neutol WA when it was available, now I use Ilford PQ liquid concentrate. I prefer the liquid concentrates because they keep better than stock solutions mixed from powders.

Good luck and keep us posted.

~Joe