In the Formula Editor, type the following text just after the database field to precede the return: chr(13).

For example, a return after the database field {Export_Custom.Dept_Po01}:
If Not IsNull({Export_Custom.F_Dept01}) Then {Export_Custom.F_Dept01} + " - " + {Export_Custom.Dept_Po01} + chr(13)+ If Not IsNull({Export_Custom.F_Dept02}) Then...