What is the most common way used in Biblical Scripture to indicate Qere and Kethib? Especially for non-Hebrew languages.
I don't think there is any single "most common way", as i've personally seen several.
Some chumashim will print the ktiv without vowels, and the kri next to it. Others will do the same, but in small print, write קרי and כתיב. Still others will only include the ktiv (without vowels) in the text, and have a note in the margin with the kri. Others use the reverse.
So as you can see, there is no one standard; rather, each publisher uses their own method.
I agree with the previous answer. I wanted to add that the Trope Trainer program that I use to learn my weekly Torah reading has a somewhat unusual technique. It has the regular Hebrew font in the right column and the Torah script in the left column. The Regular Hebrew text has the Kri and the Torah text has the ktiv. In most situations, there is a notation that there is a discrepancy, but I have found a few places where this is not obvious until you notice that the left side doesn't match the right, and you wonder why, until you find another Chumash that indicates why. It doesn't happen often, but when it does, I admit, that it's annoying.