title: Show footnote only after a pause in beamer with R Markdown
body: <p>I am making a Beamer presentation and I use pauses between contents of a single slide. I can't figure out how to show a footnote only after a pause.</p>
  <p>Here's an example:</p>
  <pre><code>---
  title: &quot;&quot;
  author: &quot;&quot;
  date: &quot;&quot;
  output:
    beamer_presentation
  bibliography: test.bib
  ---
  
  * one argument
  
  \pause
  
  * another argument^[This citation should appear only with point 2: @fargues2006]
  
  # references
  </code></pre>
  <p>with <code>test.bib</code>:</p>
  <pre><code>@article{fargues2006,
    title = {The {{Demographic Benefit}} of {{International Migration}}: {{Hypothesis}} and {{Application}} to {{Middle Eastern}} and {{North African Contexts}}},
    author = {Fargues, Philippe},
    date = {2006},
    journaltitle = {World Bank Policy Research Paper},
    url = {http://documents.worldbank.org/curated/en/508301468280735279/pdf/wps4050.pdf},
    number = {4050}
  }
  </code></pre>
  <p>In this example, the footnote should not appear when only the first point is shown, but instead when the second point is shown.</p>
  <p>I tried to apply <a href="https://tex.stackexchange.com/questions/518750/beamer-how-to-make-footnote-rule-appear-later-pause">this answer from TeX StackExchange</a> but without success.</p>
  <p>How can I do that?</p>
  <p><strong>Edit:</strong> following @samcarter_is_at_topanswers.xyz's answer, I precise that I would prefer a solution that does not require to switch from markdown to LaTeX in the document depending on whether a slide has both pauses and footnotes. However, I'm okay with using a <code>.tex</code> file or adding pandoc arguments in YAML (because I think the solution has to be this way, but I may be wrong).</p>
  <p><strong>Edit #2:</strong> I would like to put references in these footnotes with <code>@citationkey</code></p>
  <p>Also asked <a href="https://community.rstudio.com/t/show-footnote-only-after-a-pause-in-beamer-with-r-markdown/69653" rel="noreferrer">on RStudio Community</a></p>