The antecedent of the singular pronoun "it" is almost certainly not "developing career management skills" or "the planned, intentional, refective manner", since it is unclear how "developing" or a "manner" could "propose" anything. It is also almost certainly not a single "career management skill", since no such skill has been identified.
Because we can't find the antecedent in this sentence, we should look to the previous one, and we find a suitable antecedent in that sentence's subject: "this model". (Kate Bunting noted this in a comment above.) Therefore, the sentence means:
How focused are you on developing career management skills in the planned, intentional, refective manner [[that]] this model proposes?