DKIM (DomainKeys Identified Mail) is a mechanism that allows senders to associate a domain name with an e-mail message. In technical terms, DKIM is a technique to authorize a domain to associate its name to an email message through cryptographic authentication.
DKIM has the following look in your account:
In ClouDNS, you can use it by creating a TXT record.
To create DKIM, go to your DNS Zone Control Panel, click on "Add new record" and type, as follow:
Points to: DKIM-specific-text
Host: The host is given you by the domain key generator (it may be something._domainkey or only _domainkey)
Points to: DKIM-specific-text (this string here is also given by the DKIM generator)
You can see the example below: