Rechat is an email client so you can send and receive email just like you would in Outlook or Mac Mail or on your iPhone or Android.
Add your email signature to match what you use outside of Rechat in other email apps. You can either add your signature as part of the sign up process or by going to your settings section here.
Go to signature settings section here or follow below steps:
Press on your user name at the bottom left side of the page
Select Account Settings
Select Email Signature