It is difficult to validate the acitvity rates using the standard reports. You can check the activity rates at table level using the SAP tables.Tables to use for this are as below.
Tables: CSLA, CSSL, COST
CSLA - Activity master : This gives the data relating to your activity type.
CSSL - Cost Center/Activity Type : This gives the Objectnumber (CSSL-OBJNR) for each activity type & Cost Centre combination you maintained the rate. This values is concatenation of "KL", Controlling area, Cost Centre & Activity type.
COST - CO Object: Price Totals : Here you can see the rate which you entered in the fields with TK" series. TKG" is total price, TKF" is fixed price, TOG" is Variable price.
Please do comment for any suggestions & corrections.