Recommendations please!

I would like recommendations of agencies for foster care in Western PA. Especially those who would work with someone in Venango County. I am a stay at home Mom with a medical background who is very interested in doing foster care. I would love to find an agency with a social worker who is kind and easy to work with. I have four children in my home...is that too many to be considered for foster care. I would also love to hear from anyone who is presently fostering in my area and their experiences. We have three adopted children so this field is not entirely alien for me. My husband and I feel that fostering children is something we are being led toward doing...can anyone give us some guidence as to where to begin? I am hoping for agency names so please pm me with any suggestions. Thanks so much. Karen