Signatures of links

How do I add a signature or website link and make it visible to myself and others?

It appears they are gone:

There are no longer signatures after posts, however you can customize your profile (via Preferences), which people can see if they click your username. If your username is clicked from a post in a thread, your Profile Card will pop up, where you can include a farm name, etc. if you like. Clicking on the profile card will take someone to your full profile, which you can customize with more info/quotes, etc. if you’d like to include anything there.