Postgres replication: Do I need to rsync pg_xlog files if I have archiving setup in master?
That tutorial appears to be old, and also says "work in progress" at the top. I'll amend it if I have time. Please refer to the main documentation.

If you have continuous archiving set up you don't need to manually rsync the WAL, because your archive_command will do that for you.

You may also wish to consider using pg_basebackup instead of manually rsync'ing the datadir. It'll take care of everything for you over the PostgreSQL replication protocol. If you weren't using WAL archiving you'd use -X stream mode to get it to copy the WAL for you too, but you don't need that.