in LR we add one file in solution explorer, so that file is saved as witch formet?

We are using Loadrunner for record REST API web services scenario.

We are using below format:

Action()
{
web_custom_request("add_order",
 "URL=http://192.168.68.119:2015/cfs/services/ordermanager/createneworder",
 "Method=post",
 "Resource=0",
 "EncType=application/xml",
 "Mode=HTTP",
 "Body=cfsorder.xml", 
 LAST);

And we added In the Solution Explorer, .xml file as cfsorder.xml.(one  right-click the Extra Files node and select Add Files to Script to add the .xml data file.)

We gave body name as cfsorder.xml. and my application enctype= application/xml format.

So we are getting the error while re-run the script that is:

org.xml.sax.SAXParseException; Invalid byte 1 of 1-byte UTF-8 sequence.

My question is in LR we add one file in solution explorer, so that file is saved as witch formet?

please help on this

thanks,

praveen.ch