The French non-parking sign (officially designated by french trafic rules as:
"le panneau B6 a 1 Stationnement interdit") during WW2 period is the same as in use today and looks like this:
ADDITION:
These are suitable variants:
From left to right:
Non parking this side of the street
Non parking this side of the street during first half of the month (1-15)
Non parking this side of the street during second half of the month (16-31)
Non parking both sides of the street

Paul