Ref: Tips & tricks for samsung jack, which give the answers to how to add signatures for samsung jack outgoing text message, if the samsung jack support signature with the outgoing message, and how to add the signatures for samgsun jack text-messaging.
Yes, to add a signature to outgoing messages follow the steps below:
From the home screen, press the left soft key for Start Select Messaging (1) Select Messages (1) Press the right soft key for Menu Select Tools (7) Select Options (3) Select Signatures (3) From the Messages account, highlight "Use signature with this account"
then press the OK key to check the boxHighlight the Signature box then press the clear key Enter the desired Signature, using the keypad Press the left soft key for Done to save Messages account Signature