Analysing and managing workflows across organisations can be a complex task. One of the main challenges is that planners often have a limited overview of shared resources and dependencies in collaborative workflows that extend beyond their local context. In this paper, we use an emergency handling workflow across multiple organisations as a case study to demonstrate how our recently developed formal language RPL and its accompanying tool RPLTool can be adopted to facilitate decision making on resource allocation in cross-organisational workflows. We formally model the workflow in RPL, and simulate the model with multiple concurrency levels and resource configurations regarding their availability and efficiency using RPLTool, allowing the decision-makers to observe how the changes in these scenarios impact the behaviour and the performance of the workflow.