[kerouanton]

You could also "sign" using a random figure, not your real signature, after all. No? Nothing prevents you to do so, legally speaking.

[NikkiA]

You mean other than 'perjury' when they ask you in court if that was your signature?

No, it doesn't HAVE to match your usual signature, but that's not the actual point of a signature anyway.

[alasdair_]

Write "I don't agree" or something similar as your signature?