I have seen both on this site and in the Peace Corp book on Moroccan Arabic that the correct spelling of this transliteration is kanfkkr, but in use on the internet I have seen kanfakr and this seems more consistent with the pronunciation. I realize Darija is a largely unwritten and fluid language, but, why is kanfkkr correct and not kanfakr?
Shokran
Malik, welcome to the forum. Let us know a little bit about you in the new members section.
The transliteration used on the internet by Moroccans is not unified at all. You can namely see Moroccans use rather ch than sh, like in incha’allah for example, because sh is spelt as ch in French, and not at all prunounced like the English ch. (tsh)
Kanfkkr is the one that looks more correct to me. Why? Because the root is: fkkr = To think, and not fakr… this doesn’t even sound like a verb. Kanfakkar at least would sound correct too, as the MSA verb is fakkara, and in some cities, more vowels are used than in my region.
Does that make sense?
You’ll get to see that transliteration is almost a personal matter. Arabic is better written in Arabic letters, this saves a lot of trouble. Also, it’s pronunciation that matters above all.
If you need more clarification, just let me know. I’ll try to explain better.
welcomeee ya malik 
WELCOME MALIK