With Inrecruiting it is possible to keep track of the sources of origin of the candidates who view or register for each vacancy.
As regards the portals present in the Multiposting and the integration of the vacancy list on your company website, this tracking is automatic.
In case you want to share a vacancy on channels external to Multiposting or if you want to carry out a "referral" operation, just add the words "? D = referral" to the bottom of the URL of the vacancy.
ES: https://inrecruiting.intervieweb.it/Inrecruiting/jobs/backend_developer_88549/it/?d=matteo
In this way, all candidates who see this vacancy or make an application will be tracked with "matteo" source.