HOW to - Add nameservers to delegation list

I’'ve got my server configured as a nameserver, and am configuring a DYNDNS secondary nameserver. The instructions state

  1. Delegate your domain

The last step is to add our nameservers to your domain’s delegation. Using the list above, simply place these nameservers into your domain’s delegation list alongside the primary (and any other secondary servers already in operation). If you wish to run a hidden primary, you can learn more about hidden primary configuration here. Secondary DNS can take up to an hour to activate after a delegation change; during this time you should begin to see our servers query your primary and retrieve the zone file in your nameserver’s logs.

I’ve read forum posts and articles regarding setting up delegation, but can’t seem to find anything referring to delegation for secondary nameservers, only subdomains.

Also, when doing a dnsstuff domain check, I’m getting errors No NS A records at nameservers, even though A records are configured.

Your help is much appreciated, I think I am close to getting this configured.