FT once had a link to RSS threads many years ago.

Now there is a BLUE ICON to the left of sub-forums to "ADD SHARED LINKS".

What does this mean and how does one confirm it has been added?

I added 4 different links but get no alerts or messages on that thread.

I have gotten error messages sometimes "There is no application set to open the URL feed://www.flyertalk.com/forum/external.php?type=RSS2&forumids=370."

Sometimes it seems it might work with no error but I get no messages and other times I get an error.

Can someone explain how this is to work and what options there are for RSS links to threads.