The need for access to FRank in a Custom Series has been brought up more than a few times. This feature is of vital use in screener and if available in custom series would dramatically reduce the size of existing screens using FRank.
The way to get a new feature any attention is by the number of votes and resulting score. Click the link and vote, you can vote for it as vital or a lesser need level. Please click the link and VOTE! You will be very happy if we can get this.
Feature Request: FRank in custom series http://www.portfolio123.com/feature_request.jsp?view=open&cat=-1&featureReqID=1210