PostgreSql INSERT FROM SELECT RETURNING ID
You just need to add a RETURNING id to your INSERT ... SELECT:
WITH rows AS (...)
INSERT INTO dealer (user_id)
SELECT id
FROM rows
RETURNING id;
Demo: http://sqlfiddle.com/#!12/75008/1
For my purposes, I needed it in a variable so I did this:
INSERT INTO dealer (user_id)
SELECT id
FROM rows
RETURNING id INTO l_dealerid;