That's a different question than the subject of this thread and maybe one that needs more precision. Are you looking for persons lacking a "general" source, i.e., no checkmark in the checkbox beside their name in the source column of Edit Person? Or are you looking for persons for whom there is no source for any fact, general or family? The former is readily answered by using the RootsMagic Explorer Find with the criterion:
Source (general) > does not exist
The latter is more problematic because Find has no criterion such as "All facts". You can come fairly close with the following:
Source (general) > does not exist
AND Source (family) > does not exist
AND Birth > Source > does not exist
AND Marriage > Source > does not exist
AND Death > Source > does not exist
The filter has room for one more criterion so you could add one more fact type that you feel should have a source. These criteria will not eliminate a person having only sources for other facts but should get you a useful list of people you need to document.
To make a printable list of these people, you can run the report Lists > Individual List using the option "Select from list" under the "People to include" dropdown list to open RootsMagic Explorer and set the criteria as above. Alternatively, you can create a Named Group using these criteria and select the group when you generate the report.