See PUB 559  Survivors, Executors, and Administrators page 4

https://www.irs.gov/pub/irs-pdf/p559.pdf

Signature. If a personal representative has
been appointed, that person must sign the return.
If it is a joint return, the surviving spouse
must also sign it. If no personal representative
has been appointed, the surviving spouse (on a
joint return) signs the return and writes in the
signature area “Filing as surviving spouse.” If no
personal representative has been appointed
and if there is no surviving spouse, the person
in charge of the decedent's property must file
and sign the return as “personal representative

There are no provisions to sign an e-filed tax return as required and write "personal representative" .   You can only do that on a printed and mailed return (but many people ignore this requirement and e-file anyway in the decedents name.