Although one may use LaTeX’s standard \footnote command to add footnotes to slides, I don’t like the results because \footnote is really meant for the printed page, not slides. The footnote number and the separator line look out of place on a slide.

The LaTeX package textpos makes it possible to put objects in arbitrarily prescribed places on the page. Here I will describe how to use textpos to place footnote-like text on a Beamer slide.

\usepackage[absolute,overlay]{textpos}
\newenvironment{reference}[2]{%
\begin{textblock*}{\textwidth}(#1,#2)
\footnotesize\it\bgroup\color{red!50!black}}{\egroup\end{textblock*}}


This loads the textpos package and defines a new environment which I have called reference here because I use it for citing research literature. You may change the name, font size, type, and color, if you want.

The reference environment takes two arguments, These specify the footnote’s position relative to the slide’s top left corner. A Beamer slide is 128mm×96mm. That should give you an idea what to put for those arguments. A little trial and error helps. See the sample below.

Important: The call to the reference environment should occur as the first thing in the slide, before any other text is produced!

The sample file textpos-demo.tex illustrates this:

% textpos-demo.tex
\documentclass{beamer}
\usepackage[absolute,overlay]{textpos}
\newenvironment{reference}[2]{%
\begin{textblock*}{\textwidth}(#1,#2)
\footnotesize\it\bgroup\color{red!50!black}}{\egroup\end{textblock*}}
\begin{document}

\begin{frame}{Title}
\begin{reference}{4mm}{85mm}
V. Jikov, S. Kozlov and O. Olenik, Homogenization
of differential operators and integral
functionals, Springer, 1994.
\end{reference}

This is a test.
\end{frame}

\end{document}


This produces the following slide:

Remark: The use of the reference environment is not limited to footnotes. You may use it to position text or other objects anywhere on a slide.