She can create a PIN number to sign with, and let you enter it.
But, If you are e-filing, nothing needs to be included. It is a good idea if you have Power of Attorney or some other written document proving that you have the authorization to sign forms for them.
If you are printing and mailing, you can sign and put your title next to the signature. ( example, Power of attorney for Jim Jones)
https://ttlc.intuit.com/replies/6695996
