It's ok, if you apply to adjust status in USA, , you will take a

interview before the officer,your hu*****and will be here
too, so the officer won't doubt if he signed the form.However, if you take your interview in US consulate in Guangzhou,he has to sign it before VO
or a notarizer,otherwise the US government can't be sure if his signature is real.
If you have a joint-guarantor,he/she has to sign before
a notarizer.