you need to use the SRSS config tool. =>
Configuring a Report Server for Secure Sockets Layer (SSL) Connections (2005)
Configuring a Report Server for Secure Sockets Layer (SSL) Connections (2008)
"Edit UrlRoot in the RSReportServer.config File If you are using the report server e-mail delivery extension, you can create subscriptions that included a report URL in the e-mail message. To construct the report URL, the report server uses the UrlRoot configuration setting in the RSReportServer.config file. If the report runs on a report server that is accessed through an SSL connection, you must manually edit the UrlRoot to use the https:// prefix.
If you are using a server certificate, the format of the URL is as follows:
<UrlRoot>https://certificatename/reportservervirtualdirectoryname</UrlRoot>