I discovered it this week and I love it! 
Not sure how new the feature is.
It’s easy. Just put the citation inside square brackets, and then preface all that with a caret. Like this: Beanis cures cancer.^[I made it up.] It automatically takes care of the numbering and shit.
Example:
Beanis cures cancer,[1] and aliens will arrive next year.[2] More and more people are saying these things![3]
hello[1] [2] [3], it’s really neat you can do it on multiple on one portion.
goodbye ↩︎
adiós ↩︎
see you later ↩︎
Funny how the links don’t work on comments though lol, it just directs to the post’s footnotes
…Wonder if it works for comments if the post doesn’t have any footnotes though
that funny, and perhaps? It also does something weird[1] where I guess like the first one in the footnote goes back to the preexisting one? and the second one just makes a new one
with like a second footnote in the footnote[1] or [2] ↩︎
or this ↩︎