If you choose something like GMail for the app to handle the sharing, you'll get the text Mark described as the body text in the email. That's just an example of course, but when you click the share button, you'll get a list of apps available to use to share. That's where to look for that text.
Comments
Did you specify "Amazon Appstore: Kindle Fire and Kindle Fire HD" as the Target on the "App Info" tab in the copy of the app you submitted to Amazon?
Checkout <<APP_NAME>> on Amazon! http://www.amazon.com/gp/mas/dl/android?p=<<PACKAGE_NAME>>
If you are seeing something different you may not have updated the setting within the app.
mark.
Darryl