When creating an appointment, you are not able to add the Contacts as reference.
SAP Cloud for Customer
Reproducing the Issue
1. Open a new Appointment on Outlook.
2. Click Add Appointment.
3. On the new pop-up screen, click Add Reference.
4. You have 3 options: Accounts, Opportunity and Lead.
5. The "Contacts" is not an option here.
This is the system current behavior.
This feature is not supported as of now.
As it is a behavior of the system, we suggest you to raise an idea in the SAP Sales Cloud Portal requesting this functionality. The Customer Influence portal is the correct channel for requirements of changes in the system behavior. There, other customers can also vote for the idea and depending on the demand from the customer community, the developers will evaluate and plan accordingly for a possible implementation of this new feature.
Contacts, Add-in, Outlook, Appointment, Reference , KBA , LOD-CRM-GW-OUT , Outlook , How To