Can't find IIS Rewrite Rule in Config XML

Solution 1:

When adding a rewrite rules to a site it should save it in the site's web.config.

One reason I can think of why you don't see it there, is that you added the rule on the server level rather than the site level.

When done on the server level it is saved in the ApplicationHost.config file.

 %systemroot%\System32\inetsrv\config\applicationHost.config

You can also define it on the folder level, it that case it is saved in a web.config file inside that folder.