In the PENALTY EXPLANTION section it states "to request a waiver, enter an explanation.....Attach any necessary supporting documents ..... How can I attach a document?

You don't have to attach documents. TurboTax gives you lines to write an explanation.

 

If you believe you need to attach additional documents (police or insurance reports, retirement or disability documents, etc.), file your return by mail and include copies of those documents with your return.

 

Do not send the original paperwork.

 

If you file by mail, send your return by certified mail with proof of delivery.

Thanks ErnieSO for the quick and useful reply to my question. Much appreciated!