Using meteor account management alongside PostgreSQL

The project I’m currently working on needs a relational database and I chose to work with PostgreSQL using Richie765:meteor-pg. I decided to stick with Meteor’s account management. My problem is some columns in the PostgreSQL DB are foreign keys to the user’s ID(in users collection). How can I reference that to the user collection? I was thinking of every time a user successfully signups, only the relevant user data needed in PostgreSQL(userID and maybe their email) are taken from Mongos’s user collection and then stored in a users table in PostgreSQL.