Each weighmaster shall personally determine each weight entered on a weight certificate issued by him. He shall make no entries on a weight certificate issued by some other person except as allowed by regulation. Each weight certificate shall show clearly that weight or weights were actually determined. In any case in which only the gross, the tare or the net weight is determined by the weighmaster, he shall cancel the printed entries for the weights not determined or computed. If gross and tare weights are shown on a weight certificate and both of these were not determined on the same scale and on the day for which the certificate is dated, the weighmaster shall identify on the certificate the scale used for determining each weight and the date of each determination.