pdnsutil import-zone example.com db.example.com
See the official documentation for more information: Migrating (Signed) Zones to PowerDNS
pdnsutil import-zone-key example.com Kexample.com.+014+03070.private ksk
pdnsutil import-zone-key example.com Kexample.com.+014+22663.private zsk
I didn't know about this keys anymore. I found them under /etc/bind/keys. I found the description in the content of the *.key files.
root@dnsserver:/etc/bind/keys# head -n 1 *.key ==> Kexample.com.+014+03070.key <== ; This is a key-signing key, keyid 3070, for example.com. ==> Kexample.com.+014+22663.key <== ; This is a zone-signing key, keyid 22663, for example.com.