I did homology modelling with Robetta server and it generated different model. When I saved the image, it was not in pdb file it was chemical/x pdb format.The file opens with Rasmol but Now I am getting difficulty with further process (Procheck)because for the a pdb format (.pdb) is needed for that and it shows a bad file format for chemical x pdb format. Kindly help me regarding this matter.
I'm not entirely sure I understand the question. If you can open it in Rasmol, can you just convert it to a PDB there? If you really mean "When I saved the image", and it's an image file, there's no way to turn it into a PDB.