I have two maybe stupid questions, and the answer might be more abstract than I'll like, but we'll see.
First, what comprises your starting PF? I understand fine how it is calculated, and what it means, but what assets does it represent? Do you and your players maybe sit down, and discuss what bits and pieces constitute your little empire? A planet here, a factory there, shipping rights with that planet over there? If you have to liquidate something for quick cash, it might be nice to know what that something is/might be. The Winterscale Dynasty has a just over three digits Profit Factor, and we might be able to figure out what ships, loot, and enterprises stack up into it, but what about your new, just starting out team?
Second, You might start with a PF anywhere from maybe 30 to 70. Let's say you start in the middle, at 50, and possess a slightly pimped out, otherwise modest ship. After a few months of playing, what's to stop you from racking up a PF that took G. Winterscale's line (I pick on him just because he's so well known, and has the highest PF in either Lure of the Expanse or Edge of the Abyss) centuries to millennia to accumulate? I know PF alone might not represent everything you have, and the wide array of things it might consist of, but numerous missions/endeavors could net you 3-10 PF up, so it seems that, after even a dozen modest missions, you might have a PF in the ballpark of Aspyse Chorda, or one of the other successful RTs. What are some good ways, but not too dickish, to keep their PF reasonable, or maybe knock it down a peg, occasionally? When one stops to consider how much a single point of Profit Factor is meant to be worth, losing even one could seem hard to explain, without just being a jerk.
1) It can be anything. The only thing I or my group kept track of was their newly acquired PR gains. If they wanted to add to it, great. If not, then that left it open for me to use whatever Misfortune I rolled to affect them, and I kept track of it that way for future reference.
2) I utilize this house-rule that I found and edited it to my liking for my games.
1 The largest and strongest of major world hive gangs, Outcast Sects etc?
1-5 Labour Guild, Struggling Merchant House?
1-10 Manufactory Combine, Weak Hive Guild?
5-15 Minor Ministorum Sect, Hab Collective?
10-20 Hive Guild, Minor Merchant House, Planetary Level Noble House, Disgraced/fallen Subsector Noble House?
15-25 Powerful Hive Guild, Rich Planetary Level Noble House, Impoverished Subsector spanning Noble House, Poor Rogue Trader?
25-35 Lesser Rogue Trader, Weak Imperial Governor?
35-50 Greater Planetary Noble of a wealthy world, Lesser Inquisitor, Cartel of Free Traders, Typical Imperial Governor?
70-80 Mid-ranking moderately successful Rogue Trader, Average Inquisitor, Average Subsector spanning Noble House, Impoverished Major House (Sector Spanning)?
160 Wealthy & Successful Rogue Trader, Wealthy Subsector spanning Noble House, Average Major House (Sector Spanning), Impoverished Navigator House?
200-300 Legendary Rogue Trader, Average Navigator House, Wealthy Major House (Sector Spanning), Lord Inquisitor?
400-600 Noted Major Houses (Krin, Machenko, etc), Wealthy Navigator House, Lord-Sector Hax, Impoverished Great House (Segmentum Spanning) ?
800-1000 Average Great House, Impoverished Imperial House (Imperium Spanning), Illustrious Navigator House?
1000+ (?) Imperial Level Noble Houses, High Lords of Terra, Segmentum Rulers etc
Note: Simply put, all Legendary / Wealthy Houses in RT books need to, at least, double their Profit rating.