Please see this book for an overview... It has good insights and instruments to measure PC in different contexts :

Understanding Psychological Contracts at Work: A Critical Evaluation of Theory and Research, by Neil Conway and Rob B. Briner

I would start by reading Dundon et al's critical lit review of the 'PC' idea published in the International Journal of management Reviews

Psychological contract fulfillment requires mental and emotional attachment of the employees with the organization. Mere physical presence is not enough, engagement, empowerment and motivation are essential factors to establish psychological attachment leading to commitment towards contract fulfillment. Employees' expectations and organizational expectations must be in consonance, and that can happen through value based, ethical leadership creating a conducive organization culture for growth and development of the employees along with the organizational growth and development. 

Hello Dr. Gabriel:

 Psychological contracts are a bit outside of my area, but I might be able to help. Contract researchers often measure a violation or “breach,” which is the opposite of fulfillment. Thus, a measure of breach might fulfill your needs.

 With that in mind, here is a meta-analytic review that you might find helpful:

 Zhao, H., Wayne, S. J., Glibkowski, B. C., & Bravo, J. (2007). The Impact of Psychological Contract Breach on Work-Related Outcomes: A Meta-Analysis. Personnel Psychology, 60, 647-680.

 On pages 655-666, Zhao and his colleagues suggest that breaches are measured in three ways. Below, I will summarize their observations, including quoting directly from their excellent review.

 (1)  “Composite measures” provide a set of items for which a psychological contract is relevant. These items might include such things as training or pay. The composite measures then “asks respondents how much the organization has fulfilled its obligation or promise on each” (Zhao et al., p. 656).

 (2)  “Global measures” do not provide items that are relevant to “specific content” (Zhao et al., p. 656). Rather, they query the respondent in a general or overall fashion.

 (3)   “Weighted measures” list specific content information, much like composite measures. In addition, they ask “subjects to indicate the importance on each” (Zhao et al., p. 656).

 Best of luck with your research.

 -- Russell

Thanks. This is my study area and your insights have been helpful