Theres usually a small boost. If linking with a US feeder club buy a high profile US player, same for Japan, china etc. Try get a high profile player from their area to maximise profit. But i dont bother with feeder teams, usually the merchandising will increase from winning more trophies than signings.
It will help but not as much as a major Chinese player from the national team. I personally dont bother with feeder clubs for financial gains anymore as the fee payed to the club doesnt justify the income you stand to make from merchandising.