Signature is not displayed in CKEditor/TinyMCE while sending email.
1) Go to Administrator->Customize Data and Screens->Display Preference and select editor CKEditor/TinyMCE
2) Create an Individual and add email to individual and signature also. Save It
3) From Action select "Send an email" action.
4) From editor Select token = "Signature HTML"
Here signature is not added in editor which was added for contact.