Most of the signatures on the antebellum obsolete notes were hand written. The ink usually used at the time was brown, although some examples with blue ink are found, such as the signature of the Register on some notes from the Dubuque Central Improvement Company.
Shown below are a couple of notes bearing a real signature, and a third one is from a genuine note which was signed in modern times.
Signature from a 12.5 note (Phenix Manufacturing Company, 1837)
Signatures from a $1 note (Merchants and Planters Bank)
Fake Signature from a $4 note (Bank Of Augusta, Remainder)
Note the difference between signing with a pen from the 1800's versus a modern day ball point pen. Many notes were printed and escaped being issued by their respective bank. These notes are known as remainder notes and on rare occasion an example may be found where someone decades later decides to hand sign the note. Thus the fake signatures on a remainder note are not genuine from the period but rather, graffiti on the note, and detracts from it's value.