You don't need to credit HN. It was polite to ask, however. Usually I say "Hat tip to Hacker News for the link" or "Hat tip to [screen name of user] for the li

You don't need to credit HN. It was polite to ask, however. Usually I say "Hat tip to Hacker News for the link" or "Hat tip to [screen name of user] for the link" as I post something I first see here to one of my other social networks. But I only do that if the other social network includes thoughtful people who would be good participants here.