Just to clarify, are you asking where do you sign your tax return so that you can mail them to the IRS?
Yes , how can i mail my taxes to IRS
If you need to mail a paper version of you 1040 Federal Tax Returns and need to find the IRS mailing address, simply choose and click on the state you live or reside in below and see the mailing address for the corresponding 1040 form you have filled out.https://www.efile.com/where-to-mail-tax-return-form-irs-mailing-address-for-refund/
OK,do I need to sign my 140 copy form
If you are going to print your tax return for mailing then see this TurboTax support FAQ for printing a tax return for mailing when using the online editions - https://ttlc.intuit.com/questions/1944348-how-do-i-print-and-mail-my-return-in-turbotax-online