Try to calm her down if she is agitated, do so in a soothing way. Reinforce that the rape was not her fault. Avoid questions that seem to blame her for her actions. If she lives a lone, strongly recommend that a friend stay with her for at least on night. Suggest calling a rape crisis center.
All calls are confidential.
Encourage her to preserve evidence. The sooner an acquaintance rape is reported, the better the likelihood of charges being filed and the offender being convicted. It is important to do this before washing any part of the body. Treat her medical needs. Encourage her to get medical attention, even if she appears physically unharmed.