Hope this help. These are the things i did when i got a visit visa for my wife.
1. Documents:
a. Red ribbon Marriage contract, then went to Phil embassy for attestation. (100 riyals)
b. NOC from my employer.
c. Passport copy of wife.
d. My PP, and ID copy.
2. Went to immigration, went to typing booth for Application (paid 5 riyals.)
3. Went inside building No. 4, to reception for the queue number. Paid 200 riyals for one month stay.
4. Waited for 2 working days then print the visa copy online.
Am not sure how long you should be a resident to get one. In my case, i got the wife visit visa on my 5th month of residency. Salary? I have no idea of the minimum requirement.
Cheers Kabayan!