SPF to avoid Spoofing

Ok - this is going to be a stupid question I know, but it's the first time I actually use cPanel for managing email account and I do need some support while doing it. So, I've recently noticed that one of my multiple domain email address is frequently spoofed. So far it seems that emails are spoofed and sent to the same email account, and I have no reports of customers receiving spoofed email message. Anyway, I'd like to avoid spoofing (of the sender email address) and I've read it's actually possible via SPF. As all the email addresses are checked by multiple - and always different locations - I cannot filter IP addresses and a filter of the server sending the email would be enough. Is there a way to do that? How should I setup SPF in cPanel? Thanks in advance to everybody who will answer and wish you all Happy Easter. Regards g