You DO NOT need to sign OR attach a Form 1040 to your Form 1040X.
You only need to send in your Form 1040X and attach any Forms or Schedules that were "changed" along with any additional W2s, 1099's you added.
DO NOT send in a copy of your previously filed Form 1040 or newly generated Form 1040 as this will only confuse things with the IRS.
