Hello Pedapati,

Vignan AptitudeTest (VSAT) is conducted by Vignan University for admission to its various undergraduate courses. The VSAT application forms have to be submitted by offline mode with a demand draft of Rs. 1200 in favour of VFSTR. 

As for your question, the photograph should be standard passport size photo i.e. 25mm * 35mm. There is no particular dimensions for signature, just sign at the correct place in the form.