The signature allows HTML to modify the size and colour and content, but also Markup can be used. If you go to your profile page you will see a URL stating Markup which gives you help with the tagging of such like.

You don't have to be an expert, but a bit of patience will see you get what you want.

I notice some people are able to include hyperlinks and various other font/colour styles in ther signature.

Does this require HTML coding knowledge, as the signature editor only seems to allow basic text entries?

Thanks in advance.