What do you mean by teachers practice? You need to define this and explore areas related to teachers practice.

i want to observe if teachers employ reflective teaching defined by Richards in class or not

The approach described by Richard & Lockhart (1996) and others is based on looking what the teachers/instructors do, the process of preparing for the lesson, what they do and why they do, and construction of an inner or "bottom-up" view of the teaching process. Such processes are essential in observing their teaching approaches and also their willingness to collect such data about their work and their interaction with the students and their roles in teaching. Such processes can help them in forming self-awareness, self-evaluation, self-monitoring and a desire for improvement and professional growth. So inner desires trigger motives for internal evaluation and hence plans for development in teaching, and interaction.

Reflective journals created by teachers in which they reflect on these processes, thoughts, and actions can be used in the evaluation. You cannot observe all these processes as they are by nature mostly "inner" processes.