Robotic Process Automation has emerged in recent years as an important field by allowing faster and more secure processes through a reduction in the risks or errors but also an increase in the productivity rates of many industries. In this specific paper, the RPA problem aims at assigning financial transactions to software robots to minimize the total costs, incured by the licenses and utilization time. The problem is represented as a bipartite graph and the effective resistance of the graph, which is analog to an electrical circuit, is used to order the edges of a heuristic method to assign the transactions to robots. Preliminary results, based on real data from a bank, are compared to the optimal solution obtained by a linear integer programming model. They show that the heuristic method allows to obtain results quicker and that they are near the optimal solution.