When I changed my name I posted then I also put it in my profile for a good while. I figured the profile was a good way because if someone had doubts they could just go there if they wondered who the heck is this. And see that "Jimi has been known as Jimrat". You could also put it in the line how you are which shows at every post and let it be there a few weeks. I didn't do it because I didn't think of it.

But I would think even if it is not a rule, it is very nice if you put it in that field for a while or in your profile. It's much easier to spot than if it is just a post because everyone doesn't read all posts.

I did not inform my friends about my name change. I hope they didn't feel ill at ease.