Signature adjectives are listed in this post. Each word below can often be found in front of the noun signature in the same sentence. This reference page can help answer the question what are some adjectives commonly used for describing SIGNATURE.
actual, bold, certain, characteristic, chemical, clear, date, different, digital, distinctive, electronic
email, facsimile, false, familiar, fictitious, final, first, following, forged, formal, full
genetic, genuine, handwritten, illegible, individual, isotopic, key, known, last, legal, mail
mere, molecular, new, official, only, original, other, own, personal, printed, private
proper, radar, real, required, royal, same, second, simple, single, specific, spectral
such, time, unique, unmistakable, usual, written
Hope this word list had the adjective used with signature you were looking for. Additional describing words / adjectives that describe / adjectives of various nouns can be found in the other pages on this website.