My Chumash gives the reference to the Medrash Rabbah 71 (8).
In this Medrash Rabbah it's 71 (11). I see there one notarikon.
ותאמר רחל נפתולי אלהים נפתלתי וגו׳ . נופתי פתיתי תליתי אחותי עלי.
א״ר יוחנן נינפה היה לי לעשות לפני אחותי. אילו שלהתי ואמרתי לו תן דעתך
שהם מרמין בך לא היה פורש
which I understand to mean from the commentary:
נופתי I was adorned and perfumed and my couch was ready for my
marriage to Yaakov, and in my goodness I adorned and perfumed my
sister Leah instead of me on the prepared couch with my good will and
even...
פתיתי I introduced her in my stead to the marriage chamber and I gave
her the secret signs agreed with Yaakov and so
תליתי I raised up
אחותי עלי my sister over me to marry Yaakov and in the merit of this
mitzvah I merited this son.
The method to look them up is to take the reference to the Medrash and see the text of the Medrash.