Why found flyers leave things out
A found dog flyer has a different job than a lost one. You want the real owner to recognize their dog, but you do not want anyone else to be able to claim it. So the flyer never prints a name (you probably do not know it anyway), prints at most one feature, and adds "Describe them to claim" under the details.
Keep one detail to yourself: a scar, a particular marking, a collar brand or tag shape. When someone calls, ask them to describe the dog before you say anything. The real owner will know straight away.
Beware of fake owners
Most callers are honest, but some people claim found dogs to sell them or for breeding. Ask for photos of the dog at home, vet records or the microchip registration. Hand over at a shelter or vet if you have any doubt. You are never obliged to give a dog to someone who cannot show it is theirs.
Where to put a found dog flyer
Start where you found the dog: the owner is probably searching that area. Then vets, shelters and pet stores within a mile. Post the same details in local lost and found groups online. The flyer layout prints two per sheet in green, the color that says "found" at a glance.