You can't have apps on the external SD card... the Rezound has three storage possibilities:
1) Internal Storage - ~2.4GB (a "partition" of the internal 16GB flash storage) - where user data and apps are stored by default
2) Phone Storage - ~10GB (a "partition" of the internal 16GB flash storage also referred to as SD CARD in some cases) - Used for user files (music, videos, documents, etc) and where apps that can be moved are moved to via the embedded "move to phone storage" feature
3) External Storage or SD Card - 16GB (or whatever size your card is) - used for user file storage (music, videos, documents, etc) and other file storage by come some apps that specifically are coded to use it or store information here. Some apps may install data on this device.
Normally external storage (SD Card) cannot be used for apps themselves at all, this is because the phone doesn't see it as "/sdcard/" but rather a subdirectory called "/sdcard/ext_sd/". There may be apps that fool the operating system into thinking this is a native extension of Phone Storage but I have no experience in using any of them or recommendations and it might require root access. There may also be some restrictions as the external microSD card must be in FAT32 file format as well, which do not allow for Linux/Android native file system attributes (Owner, permissions, etc.).