What you are seeing is typical with foster children, as many other posters have mentioned. They have had lots of "Mom's" in their little lifetime. A 9 year old in the foster system is definately at risk of attachment issues. Attachment is on a continium, so that does not necessarily mean RAD.
There is a lot you can do to facilitate attachment. This really should be done for any new child entering a home, especially an older child. I haven't started a new book yet - but it is highly recommended: Attaching In Adoption by Deborah Gray. From skimming through this book, I think it could help new families quite a bit.
I would VERY STRONGLY encourage you to stay home with her as long as you can, maybe even homeschool for a short while. Try to recreate infancy in a 9 year old world. Become her world, become the center of her universe. Keep her by your side, within close range of you as much as possible. Cook together, bake together (slip in a little "feeding her" by giving her tastes of what you are making), do crafts together, do chores together, run errands together, read together, do her hair and nails,etc. Even if you can't stay home, do this as much as possible.
I would encourage you to keep her world small at first. Let her just focus on adjusting to you and your family. There is lots of time later on for outside activities. Certainly include her friends in your life, but at your home - keeping her in contact with you as much as possible.
Be 1--% reliable with her. When you say something mean it. Don't try to cut her too much slack, that will just create confusion and insecurity. Rules and structure provide security and safety for a child no matter how much they resist them. Her past has been full of inconsistencies and chaois, show her how different her new life will be.
There are lots of web sites you can check out regarding attachment. RAD is not the end of the world. Many attachment disordered kids do get better when they get the right help. My son, who is almost 10, is one of the success stories. I would recommend checking out Dr. Art's website:
www.Center4FamilyDevelop.com. There are lots of good articles and links there.
Good luck and congratulations! DimasMom