Actually, there was a girl on my 10u daughter's TB team that was sheer joy to watch play SS but ended up playing C because she was the best catcher. I considered it a tragedy
In rec I consider who best fits the gear and it is them....
No seriously, whoever is the loudest and bossiest are the best natural catcher candidates. I don't ask - I just hand them the gear and tell them to catch. Most of them take to it like a duck to water.
I only had to develop one, and had no plan at all. Fortunately for her, Dave Weaver was smart enough for both of us.
Success will reward the ones that do the work.
Ask the kids. Who gets bored in the OF? Then tell them catchers get to handle the ball every single pitch. Then get the NECC dvd and get to work. I would try to develop at least 2 catchers 3 would be better. Our best pitcher is also our best catcher.
Catcher's are a unique breed and tend to self-select. Start slowly. Catcher is a physically and mentally draining position. It's hot, dirty, hard work and there's no time for daydreaming or picking flowers. For newcomers, just give them an inning or two behind the plate and rotate someone else in. "Just try it for one inning" works with the reluctant girls, especially if everyone is taking a turn. Eventually 2 or 3 are asking you if they can catch more. Then you have them hooked and can start developing their skills. Good luck. There's nothing like seeing that first successful block.
If it's rec make them all try it, you never know you might find one that absolutely loves it. I had several girls last year that "had no interest" in catching. I made them all do it. Catcher was the most requested position. Now TB is different there has to be a certain skill set. Sometimes if your best pitcher has a close friend on the team that doesn't pitch it seems they are often willing to give it a go. Since they are friends already you could invite that girl to catch during pitching practices at home or with a coach etc.
When the players could not steal home we tried to get all the players to catch in a game, for our league stealing 2nd was free anyways, 3rd was a free base if it got by the catcher.
For safety reasons 2 did not catch but all the other players did. 3 of them are still plugging away at catching and are pretty good. It gets really fun for them when players are allowed to steal home and dropped 3rd strikes.