You can dampen a towel (not soaking) with lukewarm water and let her creep around in its folds to help her get some of the stuck skin off. How are you measuring humidity? How long have you had Reba? First sheds are often difficult and are more of a reflection of the care the snake had previously than the care you've given her, but you will need to keep an eye out to make sure that her eyecaps come off and to try to ensure conditions are right for her next shed.