How can I install the APK file to my blackberry bold 9700 ?
You cannot do this. What you are referring to is an Android Application Package File .apk. Theses files became popular among BlackBerry users when RIM announced that you would eventually be able to run Android application files on the BlackBerry PlayBook. Since then there have been many people that have successfully converted .apk files to .bar files which run on the PlayBook. On the PlayBook OS 2.0 you can run man of those android files as the android runtime library is built into the OS. Sorry for the long winded answer, but I hope it helps.