Here's why:
* "I" is the subject of a sentence.
* "Me" is the object of a verb or preposition.
In this sentence, "you" is the subject, and "talk" is the verb. The phrase "with Richard and me" is the object of the verb "talk." Since "me" is part of the object, it's the correct pronoun to use.
To check, you can try removing Richard from the sentence:
* Incorrect: Can you talk with I?
* Correct: Can you talk with me?