Susan asked me if I had seen that film on television on Saturday.

In this sentence, we need to change the direct speech ("Did you see that film on television on Saturday?") into indirect speech.

1. We start by introducing the indirect speech with a reporting verb, in this case, "Susan asked me."
2. Next, we need to change the pronoun "you" to "I" to match the subject of the reporting verb.
3. Then, we change the verb "Did" to "had" to indicate that the action of seeing the film happened before Susan asked the question.
4. Finally, we include the rest of the sentence, "that film on television on Saturday."

Putting it all together, we get: Susan asked me if I had seen that film on television on Saturday.