Based on my understanding, you want to configure the Report Server Web Service URL as https:// in SharePoint integrated mode, right?
In SharePoint integrated mode, we could integrate a report server with SharePoint in SharePoint Central Administration. In your scenario, you could configure https:// report server URL in Reporting Services Configuration Manager, then copy and paste the
URL into Report Server Web Service URL to specify the report server site that you want to use with the current SharePoint site or farm.
How to: Configure Report Server Integration in SharePoint Central Administration
A step-by-step example of configuring a reporting services point
for HTTPS in System Center 2012 Configuration Manager
If you have any question, please feel free to ask.