After downloading TheRecipeManager you may get an error message that says something like "Invalid checksum". This usually means that the download is incomplete or corrupted. You can check if the download is incomplete using the following steps.

First Right + Click or Ctrl + Click the downloaded file TRM_v3.1.3_Installer_DL.dmg.

From the resultant context menu select the option Get Info.

On the General panel of the Info window you will see a field labelled size. If you have a completed download this will show a file size of 51,398.890 bytes. If the size is less than this then you need to move the file to trash and try downloading again.