Before releasing your sIFR text on to the web, you should protect the copyright of any commercial fonts that you use. If you don't then you may be breaking the licence terms for that font.
You should edit the customize_me.as file before you export your .swf file. Using the settings in this file it is possible to prevent your sIFR .swf file from being used anywhere apart from on your web site.
For local testing you should set allowlocal to true. Before you upload the .swf to the web, change this to false and re-export your .swf file.
Changing the allowlocal setting will prevent somebody from downloading the .swf file and using it on their own PC and potentially taking the font file.
Next, you can set which domains are allowed to use the sIFR file.
allowedDomains = new Array("domain.com","www.domain.com");
Add the exact domains from which you wish to allow access to the file, inside quotation marks and separated by commas.
Domains must be specified in exact form, wildcard substitution is not supported.
Again, when you have changed this setting, re-export your .swf file before you upload it.