Setting up multiple VPS

We have one VPS already set up and working wonderfully (VPS1).

However we would like to delegate some tasks to a second VPS (VPS2) with another host, with access to VPS2 done through a subdomain, of which the root domain is hosted on VPS1. Nameservers are also on VPS1.

Let's say example(dot)com is hosted on VPS1, and i want sub(dot)example(dot)com to be hosted on VPS2.

The question I have, is when ordering VPS2, I am asked for a hostname and two nameservers. What do I need to set these to?

Thanks in advance.

Usually you can set hostname and nameservers later once your server is activated. Each host have their own policies and regulations in this regards.

What company are you with, the OP?

Late to the party on this one.

Let me see if I have this right;
www.yourdomain.com is at one host, while you want foo.yourdomain.com at another?

That is as simple as configuring your zonefile in DNS.

www IN A <IP address for first host>

foo IN <IP address for second host>

Or am I missing something?

You can even use proxypass on your www server to mask the hostname for the second one.