Syntax.

pdnsutil import-tsig-key NAME ALGORITHM KEY 

Example.

pdnsutil import-tsig-key foobar HMAC-SHA256 jS0fB3jI9eU1zW0sB1hQ2mK4jI8fR2dCgG4xB7mS4oG0uE5zN5oG5aS2vE7sT2dS

Syntax.

pdnsutil activate-tsig-key ZONE NAME {master|slave}

Example.

pdnsutil activate-tsig-key example.com foobar master

If you use an external backup dns server like netnod.se, that's how you can configure it.

pdnsutil activate-tsig-key example.com foobar slave