In a standard Heckscher-Ohlin-Samuelson model of international trade theory, factor and good markets are assumed to be perfectly competitive. In such a model with well-behaved linear homogeneous production technology, the shape of production possibility frontier is proved to be concave. However, once we try to weaken some assumptions of the model, for example, allowing for production technology exhibiting increasing returns to scale, the shape of the production possibility frontier is not necessarily concave. A useful diagrammatic technique has been devised by Savosnick to illustrate the efficient locus and the production possibility frontier in the same figure. However, the presentation is limited to the case of constant returns to scale technology. In this paper, we introduce an extended geometrical presentation, which enables us to deal with any types of homogeneous technologies. Furthermore, as an application, we illustrate that there is an increasing returns to scale technology such that the production possibility frontier is flat like Ricardian Theory.