Divide the dividend by the number of contracts and then multiply by the amount of your contracts.
Also I find it amazing that they even don't pay "virtual PPS" (so the theoretical amount of BTC that would be generated by 1 TH/s) but include pool luck and operator risk to the equation. After 3 months it is not very likely to have 97% of the theoretical income generated...
Another thing where the pool or bitfinex can skim off money is the apparently constantly changing(!?) total hash rate of the pool that seems to be multiplied by 1/200th to find out the ratio of the payout that belongs to Bitfinex.
Also where are the promised transaction IDs?
In their poorly spelled description they state: "Statistics regarding this pool will be posted regularly along with blockchain transaction ids will be posted and frequently updated."