From the
AnandTech Forum Guidelines (the first thread in Personal Forum Issues):
16) Signatures
a) You may have up to 6 lines of no more than 90 characters each. Blank lines count in the 6.
b) The default font size will be set at 2. You may go smaller, but not larger.
c) No url shorteners or profanity will be allowed.
d) You may have no more than one short, simple, self-promotion link.
e) You must have 25 posts before a sig is allowed.
After you have 25 posts you will be able to add a sig.