it's 'baseURL' in the TOML file, but 'BaseURL' when referenced in templates. Sigh.

config.toml

@@ -26,6 +26,7 @@ enableGitInfo = true
     goatcounterAnalytics = "gmgauthier"
     # disqus = "gmgauthier-1" # enabling this will add disqus to the bottom of all my posts automatically.
     cdnUrl = "https://gmgauthier.us-east-1.linodeobjects.com/podcast/"
+
 [markup]
   [markup.goldmark.renderer]
   unsafe= true

layouts/podcast/rss.xml

@@ -15,7 +15,7 @@
     <channel>
         <title>{{ if eq  .Title  .Site.Title }}{{ .Site.Title }}{{ else }}{{ with .Title }}{{.}} on {{ end }}{{ .Site.Title }}{{ end }}</title>
         <link>{{ .Permalink }}</link>
-        <image>https://gmgauthier.com/img/avatar.png</image>
+        <image>{{ .Site.BaseURL }}img/avatar.png</image>
         <description>Recent content {{ if ne  .Title  .Site.Title }}{{ with .Title }}in {{.}} {{ end }}{{ end }}on {{ .Site.Title }}</description>
         <generator>Hugo -- gohugo.io</generator>{{ with .Site.LanguageCode }}
         <language>{{.}}</language>{{end}}{{ with .Site.Author.email }}