I was hoping to be able to just add the dependency to include support for formulas.

The only solutions for PDF currently are to use asciidoctor-mathematical or generate DocBook and use the DocBook toolchain. Since asciidoctor-mathematical uses a native gem (mathematical), it does not work in JRuby (to my knowledge). It's possible to develop an extension for Asciidoctor that uses MathJax at build time, but as of yet no one has come forward to develop such an extension. There are other possible paths as well.

Best Regards,

-Dan