please add this record to the parcel if you have found it or you found it
I think both tenses are ok in this case but for me the first version is better because it has an impact on the present situation . Am I right?
Either use "if you find it" if you are not sure if the person will find the parcel in the future or "when you have found it" if you expect the person to find the parcel in the future.
"if you found it" is not correct.
Either it is "if you have found it" (means already found, in past) or "if you find it" (means find after you've talked to him, in future)