KF is almost certainly KiwiFarms, an infamous gossip forum where terminally online mentally ill people come together to make fun of other terminally online mentally ill people. With a large amount of doxxing and harassment accusations being thrown at it. I think harassment is against the site rules, but doxxing isn't. The site, being what it is, got itself some serious enemies. Including people with enough influence in IT space to nearly get the entire site pulled off the web.

SF is probably StormFront, an infamous neo-nazi website. Not an "anyone right of center is a nazi" kind of neo-nazi - actual self-proclaimed neo-nazis, complete with swastikas, Holocaust denial and calls for racial segregation. Even more hated and scrutinized than KiwiFarms, and under pressure by multiple governments and many more activist groups, over things like neo-nazi hate speech and ties with real life hate groups.

It would be a damn shame if archive.is fell under the same kind of scrutiny as those. I have an impression, completely unfounded, that the archive.is crew knew things were heading that way, and worked with that in mind for a long time now. But that doesn't guarantee they'll endure. Just gives them a fighting chance.

SF could be suicideforum

KF would be KiwiFarms

They're under a CSAM flood/reporting attack themselves, according to their admin.