Adding custom buttons to the CKEditor in Email Form

Hi All,

I have added the CKEditor in the description field of my email form. Now I need to add three custom buttons as following in the CKEditor.

1. Insert Template

2. Insert Article

3. Insert Signature

These three buttons are already available in the existing HTML editor in email form as shown below in red.

But I need to enhance the below form using CKEditor and also add these three buttons to it.

How shall I do this?

Any help is appreciated.

Thanks and Regards

Nithya