So the feed has to exist, is that a problem?
Point it to an empty feed from some domain, as long as it exists
or
Download one of your XML feeds to your harddisk and empty it of <item>
s using a text editor. Then upload it somewhere as something.xml
and point FB there.
or
Upload this somewhere as something.xml
and point FB there.
<?xml version="1.0" encoding="UTF-8"?>
<rss version="2.0" xmlns:content="https://purl.org/rss/1.0/modules/content/" xmlns:wfw="https://wellformedweb.org/CommentAPI/" xmlns:dc="https://purl.org/dc/elements/1.1/" xmlns:atom="https://www.w3.org/2005/Atom" >
<channel>
<title>Your Site Name</title>
<link>https://www.yoursitedomain.com/</link>
<pubDate>Sun, 30 Mar 2008 15:16:42 +0000</pubDate>
<generator>https://www.ads-software.com/?v=2.3.3</generator>
<language>en</language>
<atom10:link xmlns:atom10="https://www.w3.org/2005/Atom" rel="self" href="https://www.yoursitedomain.com/" type="application/rss+xml" />
</channel>
</rss>
I hope this helps.