The total number of subjects is 36 with ID numbered from 5001 to 5050 (some ID number was missing). I'd like to bootstrap the data set by subject ID to form a new data set containing 100 subjects with ID numbered from 1 to 100.
Go to support.sas.com and search for bootstrap to get lots of guidance on it's use.
Usually, bootstrapping does sampling with replacement to get 'sample' that is the same size as the original. I'm concerned that changing the sample size will artificially reduce the variability and bias the inference. Efron & Tibsurani (An introduction to the bootstrap) is a classic reference.