You don't. Whether or not it makes money is based on the overall stats of the planet - primarily the flats/jobs ratio. Then you just need to open it to everyone and have someone operating it. Oh, and have it powered. Then you get money each month.
Or lose money, if the planet has bad stats. If you own the city, you can see the stats. If you don't, either ask the person who does, or just open it and find out.
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"May the Grace of Ara go with you, and His Vengeance be wrought upon your enemies."
If you visit, whoever owns the majority of the facilities in the city probably also owns the city. You could send them a message to ask them for the planet stats. Or find someone else with a facility there and see if they've been getting income.
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"May the Grace of Ara go with you, and His Vengeance be wrought upon your enemies."
The house you control is on Obra-Skai, which is viewable on the galaxy map at http://rules.swcombine.com/galaxy/planet.php?planetID=327
The stats I have as city-owner are;
Civilisation Level: 0.65%
Morale: 100%
Crime: 0.58%
Employment Rate: 224.4 / (229.0 + 0.1) = 0.97948
I *think* I've been hearing from the other people assigned to residences on the planet that they're earning around 1500cr/month, but I've also heard that somebody with a cathedral assigned to them racked up a debt, so I'm not sure. I should doublecheck the cathedral was on the same planet.