also consider .Rmarkdown source files

Author: yihui

layouts/partials/footer.html

@@ -5,15 +5,20 @@
   {{ replace . "{Year}" now.Year | markdownify}}
   {{ end }}
   {{ if .File.Path }}
-  {{ $RmdFile := (print .File.BaseFileName ".Rmd") }}
-  {{ if (where (readDir (print "content/" .File.Dir)) "Name" $RmdFile) }}
-    {{ $.Scratch.Set "FilePath" (print .File.Dir $RmdFile) }}
-  {{ else }}
     {{ $.Scratch.Set "FilePath" .File.Path }}
-  {{ end }}
-  {{ with .Site.Params.GithubEdit}}
-  | <a href="{{ . }}{{ $.Scratch.Get "FilePath" }}">Edit this page</a>
-  {{ end }}
+    {{ $RmdFile := (print .File.BaseFileName ".Rmd") }}
+    {{ $Files := readDir (print "content/" .File.Dir) }}
+    {{ if (where $Files "Name" $RmdFile) }}
+      {{ $.Scratch.Set "FilePath" (print .File.Dir $RmdFile) }}
+    {{ else }}
+      {{ $RmdFile := (print .File.BaseFileName ".Rmarkdown") }}
+      {{ if (where $Files "Name" $RmdFile) }}
+        {{ $.Scratch.Set "FilePath" (print .File.Dir $RmdFile) }}
+      {{ end }}
+    {{ end }}
+    {{ with .Site.Params.GithubEdit}}
+    | <a href="{{ . }}{{ $.Scratch.Get "FilePath" }}">Edit this page</a>
+    {{ end }}
   {{ end }}
   </footer>
   </body>