League of Legends, now known as one of the largest games there are, implemented a recruit-a-friend early in post-launch development. They had small rewards and absurd rewards and something in-between. Here's the thing: They grew from ~100k players to ~1.5m players in the cycle of 5-6 months. (February -> june-ish, can't find any information of when the RaF-system was put in place)
An example of one of their most absurd rewards was 10 000 referrals. If you managed to get 10k to play LoL, you'd get an all-expenses paid trip to Riot Games HQ to chill out with the devs and create your own champion with their help. A smaller reward, 25 referrals, gave you a "recruiter" forum title. Also, the recruits had to reach level 5 with their "summoner", an avatar that represents the player who is controlling the champions on the battlefield. How could this system be implemented into Salem? Well, why I am by no means a game dev, and some of these suggestions may be complete *****, I have some suggestions:
First of all, you will only get an additional tick on your counter of recruits when they reach a point of some form of character development. In League, reaching level 5 could take around 4-7 hours, as each game is usually around 40 minutes and you level up slightly slower than a level per game early on.
My suggestion is that the recruit has to attain 20-25 biles in all and learn one intermediate skill (not all, there will be a list of what kind of skill is required, , such as backalley pugilism, field dressing, prospecting etc.
For each recruit reaching this goal, you gain 100 silver.
For a total of 5 recruits, you get a mystery hat box.
10 recruits, weapon box.
25 recruits, store pack of your choice.
2500 recruits, highest reward, design a skill or combat move or something of the like with MM.
There are just examples to get a feel of what they could be. I, by no means, claim they are the right number or right rewards.