How do you dictate a signature?
Well .. I'm assuming the person who was doing the typing was the same person who made the signatures.
If Burkett had documents with Killian's name on it, he would have just had to request a signature block.
I could create a letter or memo from dictation. However, the person doing the dictation is required to specify the format to be used .. and if not .. a common or standard is used. In Burkett's mental state, he may not have even realized the person doing the typing didn't know what the standard form was .. but it definately was not a military person.