You can create a personal signature for every brand within your Re:amaze account. Re:amaze will pull the relevant signature whenever you reply through an email channel that belongs to a brand.
To start editing your personal signature, simply go to the "Settings" menu and click on "Signatures" under "Personal Settings".
Signatures can be formatted in markdown.
The email passthrough feature will allow Re:amaze to hide your signature in favor of the signature available in your email client.