LPT: if you need to find an RSS feed of a site, just search feed:<name of site> on bing
for example if I need to find the rss feed of lwn.net I can search feed:lwn.net to get the result https://lwn.net/headlines/rss, you can also use duckduckgo but it includes irrelevant results for some reason, it should also work in searx.
Great advice ! And just to add, a a searx user, if bing is among your engines, you can do the same while adding '!bi' to the query (which specifies to only look for results from bing) and you should get the same result, I just tested it !
[EDIT : I kept testing and it seems like it doesn't work on all searx instances, but I haven't really figured out why. searx.mha.fi is one of those where it works. ]