Reference Architectures (RA) in a Software Product Line (SPL) context are generic schemas that can be instantiated to configure concrete architectures for particular software systems or products of the SPL family. SPLs claim to be reusable industrial solutions to reduce development cost and time to market; however their development requires a huge effort, since the RA must be evolutionary. The goal of this work in progress is to present a practical RA domain engineering method for the Human Resources domain based on a bottomup strategy applied to the early Scope phase of SPL Engineering. A usual industrial practice in this development is to start from a single existing product built by the enterprise and incrementally derive the RA by adding new elements. Four architectural configurations are developed and quality properties are considered early as major responsible of the SPL variability. Our approach is applied to a real industrial case study.