It appears to be a later date Robinson, perhaps as late as the end of 1960's. Robinson often used a steel tip ink pen which is what this appears. The way he rendered the "rd" points to a later signature along with the overall formations. His earlier signatures are usually more well defined and articulated.
So very kind, Thank you. Here is my Robinson for you to see. I am sorry I do not have a better scan to post. It is 5" x 7" and double weight matte finish.