Ah, thanks for explaining. I went searching for the book containing your name in the Lodge image and came up with this
https://books.google.com/books?id=EVsVAAAAQAAJ
Same wording but different book.

"verified by his signature "at full length" indicates you could not join a Lodge signing "David Merrill"

It is interesting they do not allow a man his own signature. I did have a bank balk at the way I signed a document once, in front of a notary no less.