{{Cite web}} and similar templates can also be used outside of a <ref>
tag, e.g. on a page like this:
https://en.wikipedia.org/wiki/Review_aggregator#Bibliography (not the
greatest example, but the best I could find quickly).
If you want it inside of a footnote, it's a bit complicated in visual
mode, since the footnotes can be reused multiple times. The way it works
is that there is a separate place in the document where the contents of
every reference are placed (the "internal list"), and the location of
the <ref> contains only a small node that links to the internal list.
Manually constructing the data so that both these things refer to each
other would be a pain, but there is a helper class that makes it more
convenient, ve.dm.MWReferenceModel.
You'd use it like this:
https://phabricator.wikimedia.org/P10018
I adapted that example from the code in
ve.ui.MWCitationDialog.prototype.getActionProcess, which is how VE
itself inserts new references.
Hope that helps (and doesn't look too awful).
--
Bartosz Dziewoński