Yes. 1 The effect of signature is confirmation, and there is no need to stamp it. The validity of a contract is used to confirm whether the behavior is valid in the event of a dispute. The validity of your signature is that you confirm that the delivery is valid. As long as you can confirm that you have signed this name, then this has been established.
If the quantity is not up to standard, it is your fault to sign. If you want to sue, then you have to bear the burden of proof, that is, to prove that the other party did not bring enough things, and there was no clear confirmation or coercion when signing.