Hello. I am getting married next October and I wanted to know if it is Halacha or tradition that a man signs the ketubah. I would like my religious Shomer Shabbat married female friend to sign the Ketubah and I wanted to know if this is ok.

Mazal Tov! The Ketubah is a Halachic legal document and requires the signature of two Halachacly valid witnesses. A Halachacly valid witness has to be a free Jewish male, over the age of 13 that keeps the laws of what he is attesting for, honest and not related to whom he is testifying for or to the other witnesses. Your friend may fit all requirement but one.