When trying to save a message as an oft-file (when creating a reply template for a message rule), I don't get the option to save it as an Outlook Template.
How can I enable this?
The option to save as an oft-file is only available when you are using Outlook as the email editor. Currently you have it set to Word.
You must change your email editor to Outlook when creating the template. After this, you can switch it back to Word again.
To change the email editor;
Tools-> Options...-> tab Mail Format
Note: This post doesn't apply to Outlook 2007 and later as these versions of Outlook only have one editor which allows you to save in the oft-file format. In Outlook 2007 press the Office logo in the left top corner and choose Save As. In Outlook 2010 and Outlook 2013, you can use File-> Save As