1. Clone the repo into some directory (~/rtl-433-openwrt for example)

2. To get the latest rtl-433 sources change PKG_SOURCE_VERSION in the Makefile

3. Adding src-link into the feeds.conf has never worked for me so I'm creting a symbolic link manually:

   cd package/feeds/packages/
   ln -s ../../../../rtl-433-openwrt/utils/rtl-433/ rtl-433

4. Compile

   make package/feeds/packages/rtl-433/compile V=99

5. Create the package in bin/ar71xx/packages/packages/

   make package/feeds/packages/rtl-433/install V=99
   

6. Copy created ipk package to the router and install it with:

   opkg install ./rtl-433*.ipk

   It will complain about missing librtlsdr. So install the library from the repository or compile and install it yourself before installing rtl-433 package.

7. rtl-sdr package could also be compiled or installed from the repository

   # Compile and create an ipk package
   make package/feeds/packages/rtl-sdr/compile V=99
   make package/feeds/packages/rtl-sdr/install V=99
   
   # Install from the repository
   # It will automatically install librtlsdr library
   opkg update
   opkg install rtl-sdr