DKIM for Hestia hostname

Hi,
How can we configure DKIM for the hestia’s hostname if it is a subdomain? As far as I know Hestia generates same selector for each domain, So I can’t simply add hestia’s hostname (hestia.domain.tld) in mail and use DKIM as it would have same selector of the main domain (domain.tld)

This should also fit for hestia: https://serverfault.com/questions/851215/setting-up-spf-and-dkim-records-of-a-subdomain