@jd at definitely.cn/content/a... is a reply to the post on your Jekyll blog. That probably didn’t get here because of which RSS feed(s) are configured

I don't understand how WebMentions are supposed to work between two self-hosted microblogs that are integrated with micro.blog. If I want to reply to a self-hosted post appearing on micro.blog, do I send a WebMention to the micro.blog conversation, the self-hosted post, or both?