What is the process to obtain the Kor Ror 22 document for a Non-Immigrant O visa extension in Thailand?

Let's simplify this.

*** If you were married OUTSIDE Thailand, then yes, you need to get your marriage documents translated and legalized through the Thai embassy in your home country and then co-legalized by the Bangkok MfA in Thailand, before you can go to an Amphur and get it registered inside Thailand.

Then your marriage registry printout would be the Kor Ror 22.

A Kor Ror 2 registry printout would apply to a marriage that was sealed and registered inside Thailand.

*** If you married INSIDE Thailand, you will never need, and can never get, a Kor Ror 22.

*** On the other hand, if you married OUTSIDE Thailand, you cannot get a Kor Ror 2, because you need a Kor Ror 22 for a marriage registration you brought to Thailand from abroad.

But let’s assume that the marriage was done INSIDE Thailand.

In that case all you need is for your Thai spouse and you to visit the Amphur, she with her ID card and blue housebook, in order to obtain a Kor Ror 2, which is the regular marriage registration document for a marriage that was registered inside Thailand.

The fee is 20 Baht. No need to legalize at an embassy or MfA for the use on Immigration inside Thailand.

The original rose border marriage certificate you got when you got married INSIDE Thailand is a Kor Ror 3.

Immigration does not accept it as proof of a still existing marriage, because theoretically you could already be divorced and be tempted to use a long invalid Marriage Certificate as a proof for the application to a one-year stay permit.

1st time apply? My immigration told me i can only apply non o outside thailand

You get it from your local amphur