Propensity modeling is such a broad term. From your question it seems like what you really need is some clustering technique reference.
In general I really like Data Preparation for Data Mining using SAS by Mamdouh Refaat. Many topics discussed in this book apply across the board to all commonly used techniques, including Cluster Analysis.
My go-to book for clustering using SAS is actually SAS' training material from their Applied Clustering Techniques course. SAS has at least another couple of cluster related courses, which I have not attended and cannot really speak to. There is a Customer Segmentation using EM, and a Propensity Score Matching one.
G