There are a few options for how to get to David from whatever country you are visiting. David is located in the Chiriqui Province, in the western region of the country. It is an approximate 45 minute drive from the Costa Rican Border.

If flying in to Panama City's Tocumen International Airport (PTY), you would have to shuttle across town to the Marcos A. Gelabert International Airport (PAC) - more widely known as the Albrook Airport - to get a connecting flight to David's Enrique Malek Airport (DAV).
Airlines making this leg of your flight are Air Panama and Aeroperlas.

You could also fly in to San Jose, Costa Rica's Juan Santamaria International Airport (SJO) and get a flight from Air Panama to David. You would not have to switch airports in San Jose.

Or, if you're feeling really adventurous and have the time to spare, you could take the 6-7 hour bus ride cross country from Panama City. The bus terminal is located in the Albrook Mall.