Westerner bringing family to Riyadh

You need to have the following to apply for Iqama for your family:
1) Your education certificate, marriage & birth certificate attested by Saudi embassy of the certificate issuing country and then attested by the ministry of foreign affairs here in Saudi. It needs to be translated to arabic after all this before submission for iqama.
2)Letter from your employer
3)Application form filled in arabic
4) Passport copies of your family
5) Nowadays they are asking for GOSI certificate as well. (Your HR can get this for you. Or you can get it yourself ,its available online)
6) pay 2000 Sr as fees

Most of the stuff above your HR will arrange for you or help you with.
You just need to get your education, marriage and birth certificates attested by the Saudi embassy in the certificate issuing country. Rest everything wont take much time.
All the best

Thankyou for your thorough reply. My qualifications have already been attested by the Saudi embassy before i arrived in the country. Will the visa they be given mean theyll have to leave the country every couple of months? Also, How long does this usually take once all the paperwork is submitted?

The visa you get by this procedure is resident visa aka iqama. In this type of visa you can stay in the kingdom for as long as you like without having to travel outside the kingdom every 3 months or so.
This issue of travelling outside kingdom  is for visit visa. Applying for visit visas is pretty straight forward, you can apply online without any certificates or other documents. After it gets approved (usually in 2-3 days, maybe less) you can stamp the visa from your home country. You just need to have your marriage/birth certificate attested at this time. No other documents required. But you need to exit the kingdom every 3 months.

You need to weigh the pros and cons for visit and resident visa yourself before deciding.  The most obvious benefit of visit visa is you don't have to pay dependent levy and the convenience of leaving the kingdom without making an exit re entry visa first. However you can't enroll your kids in school or have proper medical coverage etc on visit visa.

Coming to the second part of your question for resident visa (iqama), after you have all the documents sorted (you need to have the original and a copy each of all the attested documents with you, they'll keep the copy and return the originals) take an appointment and visit the istiqdam office in your city (taking someone from your HR is highly recommended although you can by yourself as well). If all documents are in order they will approve your visa and give you an approval paper instantly. Send a copy of that approval paper to your home country, and submit your family's passport along with the approval paper to the Saudi embassy/consulate to get the visa endorsed (you need to mention which Saudi embassy/consulate in the application form they will give you the approval paper accordingly). Your family might also need to do a medical screening in your home country.

Hope this helps.

Thanks very much. I think for the sake of time we'll be doing the visit visa. Your info has been very helpful. Just on the point of leaving and coming back every few months, is there any paperwork that needs to be done?

Also, I understand that people on visit visas can not work in the kingdom . If they were to want to apply for jobs what would be the process? Is it best if my wife had the intention to apply for work to attest and notarise her degrees in UK before coming or bring the originals with her to Saudi and do it all here?