It is the owner's responsibility to post either a handwritten sign or a professionally made sign to warn unauthorized people that their vehicle may be towed if found parking on their private property. Please note that a sign permit may be required for this type of sign and sign location.
For information about quoting specific bylaws on a no parking sign, contact the Toronto Police Parking Operations Support Team. The parking bylaw office will advise on the sign wording, dimensions, colour etc.
To have a no parking sign made, contact a private sign company. The City of Toronto cannot make recommendations. You can try searching on-line or consult your local business directory.