How do I vouch for a Friend?

If military, invite them.
http://screencast.com/t/XvZrOWc3c

When they go to validate their profile, they can list you.
Check this Support article
How do I verify my account
http://support.rallypoint.com/customer/en/portal/articles/1342956-how-do-i-verify-my-account-

which says in part "4) Get vouched for by a member


If you know someone already on RallyPoint, you can ask them to vouch for you by entering their email address in the field provided. This will only work if you use the email they used to set up their account. Please note that only highly trusted members of RallyPoint may vouch for you, and not all members. Highly trusted members are those who have gone through more rigorous screening as part of the RallyPoint community, beyond basic verification. Please note that for the privacy of our members, we obviously don't display anybody's email address. When you click "Send" we will send them an automatic email asking them to verify your account and provide a direct link to do so. "