Question DKIM signature sending mail from two servers

[MicheleP]

Server operating system version

centos 7

Plesk version and microupdate number

18.0.44

Hi
I have a domain with mail server on server A but sometimes I send mail from server B (for newsletter)
Both server have plesk and both server have external DNS service
SPF is ok, the ip of server B is also is in the spf dns record (<spf>pass</spf>)
But the dkim check fails (<dkim>fail</dkim>)
There is a way to sign the mail sent by server B with a DKIM signature referred to the domain on server A?
Thanks