Powder samples of the ternary carbide ErMn4Fe8Cx-1 were oriented under a low magnetic field H similar to 0.5 T. Analysis of the crystallographic texture of the samples confirms that the compound is of easy plane type, in agreement with magnetization measurements and neutron diffraction experiments performed elsewhere. Both the latter techniques have revealed that the magnetic arrangement is rather complicated, as supported by competing contributions to magneto-crystalline anisotropy. However, assuming a reasonably simple expression for the magneto-crystalline anisotropy valid at high temperature only, the texture analysis performed at 300 K, has allowed simulation of the anisotropic magnetization curve for this planar ferrimagnetic structure. A comparison with the experimental magnetization curve reveals the onset of a first order magnetization process (FOMP) taking place under an applied field up to 1.8 T. The occurrence of this FOMP should result on the competition between different contributions to the magneto-crystalline anisotropy energy.