Criminal Law Questions? Ask a Criminal Lawyer.
you can apply for the RO in California by going to the clerk of the court and requesting the form for the RO. the respondents will need to be served in OK. this will need to be done by a the local OK sheriff. so once you get your Temp Order, you take it to your sheriff and they pass it on to the sheriff in the county where the respondent's live. the document will give them a court date to appear in CA to show cause why it should not be made permanent. if they do not appear, then a court can issue the RO permanently on a default. once that is granted, they cannot contact you via in person, by mail, phone or other means while in CA.
when you file the affidavit, you must be sure to state the reason for the RO in that you are in fear for your life and/or wellbeing that they are threatening and how.