What I am looking for is that I would like to add a message on Note/Rich Text field. So user will have idea what information he should put in the field.

You can see below screenshot what I am looking in the Note field where it is the multiselect field in creator.Here you can see there is a message "Select multiple Values". 

I would like to have the same in the Note filed but different message.

Thanks for your help.

Arfater.