URL ReWrite configuration redirect all .htm to .cfm

We have Micrsoft's URL ReWrite installed on Windows Server 2012 R2 IIS 8.5, and wish to redirect system-wide any incoming traffic to any .htm file to be directed instead the corresponding .cfm file located in the same folder.  The .htm files existed previously but we can't seem to get .htm to work, even after changing the Handler Mappings and other CF Files others have recommended to edit.

The following  is not working for me. There is no  error but the .htm file which has ColdFusion code, does not process or redirect to the .cfm file. There are too may .htm files system wide to change easily.

I'm editing the web.config file directly because the IIS URL ReWrite is just far too alien for me.

What am I doing wrong in my code? Please only respond if you can see what I'm doing wrong and you believe you have a fix in the web.config file, or can show me exactly how to use the IIS 8  URL Rewrite Module to get this done.

This web.config file is in our web root directory and also where the .htm file is located we're testing.

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
   <system.webServer>
<rewrite>
     <rules>
  <rule name="htm to cfm" stopProcessing="true">
    <match url="(.+).htm$" />
    <action type="Redirect" url="{R:1}.cfm" />
  </rule>
</rules>
</rewrite>
         <defaultDocument>
            <files>
                <add value="default.cfm" />
            </files>
        </defaultDocument>
        <security>
            <requestFiltering>
                <fileExtensions>
                    <add fileExtension=".cfm" allowed="true" />
                    <add fileExtension=".htm" allowed="true" />
                </fileExtensions>
            </requestFiltering>
        </security>
    </system.webServer>
</configuration>