See if this helps:

http://www.empirisoft.com/support/showthread.php?t=107

Also, check out the section on min-max in the user's guide. If every image is shown for a constant time like 300ms, then set the min-max value for that trial to 0-300! which will have DirectRT continuing automatically after each 300ms segment. You will end up with an RT for each image though which may or may not be ok to you. If not, then consider the animation strategy referred to in the link above. Let me know if that helps!