Despite the emphasis on effective supervisory feedback formulation on postgraduates' academic writing, our understanding of effective feedback forms may not be comprehensive without mentoring students' responses to feedback. Therefore, the current case study explores feedback formulation on research proposal writing and two postgraduates' responses to feedback in a Malaysian university. Data were collected from written feedback, students' commenting responses to feedback, their text revisions, and follow-up interviews. The feedback is formulated as directive, referential, and expressive, and it addresses issues related to content, organization, linguistic accuracy, and appropriateness in research proposal writing. The two postgraduates engaged in cognitive (e.g., confusion), metacognitive (e.g., reading feedback), and affective (e.g., appreciating feedback) responses to feedback. They integrated most of the feedback in revising their writing and made additional text revisions. Although this study is primarily qualitative in nature, simple descriptive quantitative measures were applied to the data to determine the prevalence of feedback forms, responding and revision patterns. The study provides useful suggestions for supervisory feedback practices.