This is in man ranger:

@

Open the console with the content "shell %s", placing the cursor before the " %s" so you can quickly run commands with the current selection as the argument.

So,

1. highlight the files you want to work on with Space

2. type @ to get to a command prompt which will be :shell %s with the cursor positioned before %s

3. type the name of your command and press Enter

4. the command you specified will be executed with selected filenames as parameters

This is in man ranger:

@

Open the console with the content "shell %s", placing the cursor before the " %s" so you can quickly run commands with the current selection as the argument.

So,

1. highlight the files you want to work on with Space

2. type @ to get to a command prompt which will be :shell %s with the cursor positioned before %s

3. type the name of your command and press Enter

4. the command you specified will be executed with selected filenames as parameters

The man page also covers adding a pause to check command output:

FLAGS

There are some additional flags that can currently be used
only in the "shell" command: (for example ":shell -w df")

 p   Redirect output to the pager
 s   Silent mode.  Output will be discarded.
 w   Wait for an Enter-press when the process is done