RapportDB Primary Filegroup Full

WDM 4.9.0 Standard version on W2K8 R2 server;

When opening console program, the error message is displayed:
[-2147217900] WriteSystemLog: Could not allocate space for object 'dbo.SystemLog' in database 'RapportDB' because the 'PRIMARY' filegroup is full. Create disk space by deleting unneeded files, dropping objects in the filegroup, adding additional files to the filegroup, or setting autogrowth on for existing files in the filegroup.

Since this is the Standard edition - and SQL Express - it looks to me as if the database is bumping up against the 4Gig limit. However, I have no way of knowing which files I can eliminate or which to add.

Anyone know how to resolve this?
TIA
Rick