Systemic sclerosis (SSc) is a rare autoimmune disease in which many patients experience Raynaud's phenomenon (RP) - painful episodes where commonly fingers or toes change color and become painful, numb, or tingly, usually triggered by cold or stress. This open-label study is testing an inhaled powder form of treprostinil (LIQ861) to find out which doses can be taken safely and comfortably by adults with SSc who have frequent symptomatic RP attacks. About 75 adults will be randomly assigned (2 to 1) to either a dose-titration group or a fixed low-dose group. The study also explores whether treatment reduces the number, severity, and impact of RP attacks. The main goal is to identify tolerated dose(s).