When submitting papers, journals often require double-spaced footnotes. While there seem to be different approaches to it, this one worked quite well. It requires the footnotemisc package. You simply need to enter the following code in the preamble of your LaTeX file: 

\usepackage{footmisc}
\renewcommand{\footnotelayout}{\setstretch{2}}

See also: Original Source by Jan Sauermann

Note: The copyright belongs to the blog author and the blog. For the license, please see the linked original source blog.