A theoretical framework specifies which key variables influence a phenomenon of interest and highlights the need to examine how those key variables might differ and under what circumstances.
Having a theory helps you identify the limits to those generalizations. Therefore, note why the framework you've chosen is the appropriate one. The research problem anchors your entire study and forms the basis from which you construct your theoretical framework.
For example, Peripheral Realism Theory, which categorizes perceived differences among nation-states as those that give orders, those that obey, and those that rebel, could be used as a means for understanding conflicted relationships among countries in Africa.
Do not leave the theory hanging out there in the introduction never to be mentioned again. They want to know the following: Your understanding of chosen theories; Why you choose a particular approach; Your knowledge of theories; How you use them; Possible downsides.
By virtue of its applicative nature, good theory in the social sciences is of value precisely because it fulfills one primary purpose: to explain the meaning, nature, and challenges associated with a phenomenon, often experienced but unexplained in the world in which we live, so that we may use that knowledge and understanding to act in more informed and effective ways.