[bokumo]

What LaTeX package does one use to get the "back" link at the end of footnotes like the linked PDF exhibits?

[gurjeet]

Yes, that's an interesting implementation. I'm using Firefox, and the jumps to the notes and back to the paragraph are recorded in history, and has the expected effect when clicking the back and forward history arrows/buttons.

[evomassiny]

hyperref does this with the "\ref{}" command, it can link to any defined \label