I tried all methods from this question: How to change font family in footnote? and none of them work for me...
The command setting the desired size is
As default, beamer loads
Just to let you know what's the orignal. You could redefine
Instead of the simple example
If you only want to change the footnote text size for a single footnote, as one occasionally has to do when citing long URLs, the
The footnote in this example would be set to 80% of the normal size.
The "official" method to change the \footnote font size is a call to
A complete example: