What is atma krit: In Jainism, some texts describe karmas as being of types based on who authored them. "Krit" karma means a karma that is caused or done by the soul itself through its own thoughts, speech, or actions with intentional involvement. In other words, these are karmas that originate from the jiva’s own volition and conduct.
How it fits with other karma types: Besides krit, there are mentions of karit (done by others) and anumodan (approved or sanctioned by oneself). All such karmas bind the soul and affect its journey through samsara, until they are stopped (samvara) and shed (nirjara) on the path to liberation.
Tradition note: Both Digambara and Śvetāmbara traditions affirm that the soul is the busy agent in the bondage of karma and that liberation comes from purifying faith, knowledge, and conduct. The exact classifications of karma (including krit, karit, anumodan) appear in Jain explanations of karma, and differences between traditions are mainly in disciplinary details rather than in the fundamental idea of atma and karma.
Simple takeaway: Atma krit refers to karmas that the soul binds to itself through its own deliberate actions and inner disposition.