Robotic Process Automation (RPA) is a technology that creates software robots emulating human interactions with computer software to automate low-level, routine tasks in business processes. The integration of RPA technology within Business Process Management Systems (BPMS) improves process automation at operational level and accelerates digital transformation in modern organizations. Existing research has proposed various solutions to streamline a low-cost integration. But they require modification of the existing process models and do not fully support the use of RPA bots as active resources in process execution. In this paper, we present an integration framework for RPA within BPMS that address those gaps. The framework is designed following the established Workflow Reference Model (which underpins BPMS) and supports two ways of having RPA bots as active process participants: acting as “digital employees” that can independently complete process tasks as human resources, or acting as “human assistants” that collaborate with human resources in completing tasks. We implemented the proposed framework as an open-source software prototype and evaluated its feasibility through a use case of bank account opening process.