In a (t, n) threshold proxy signature scheme based on RSA, any t or more proxy signers can cooperatively generate a proxy signature while t-1 or fewer of them can't do it. The threshold proxy signature scheme uses the RSA cryptosystem to generate the private and the public key of the signers. In this article, we discuss the implementation and comparison of some threshold proxy signature schemes that are based on the RSA cryptosystem. Comparison is done on the basis of time complexity, space complexity and communication overhead. We compare the performance of four schemes: Hwang et al., Wen et al., Geng et al. and Fengying et al with the performance of a scheme that has been proposed by the authors of this article earlier and proposed an advanced secure (t, n) threshold proxy signature scheme. In the proposed scheme, both the combiner and the secret share holder can verify the correctness of the information that they are receiving from each other. Therefore, the proposed scheme is secure and efficient against notorious conspiracy attacks.