Adding a watermark

Have you considered making a custom pattern preset from your watermark?

https://helpx.adobe.com/photoshop/using/creating-patterns.html

1. After you've created the pattern preset, create a new layer on top of your image. 

2. Use the Pattern Stamp tool in multiple random areas and set the blend mode to Overlay.

The reason for doing it this way is to make it harder for algorithms to automatically detect and remove your watermark. And while this doesn't protect images from theft (nothing does), it makes them a little less attractive to would-be thieves. 

The other option is digital barcoding which is un-detectable by humans.

https://helpx.adobe.com/photoshop/using/digimarc-copyright-protection.html

I'm posted a script that can add  your watermark to any size images. You could customize it for your watermark and the assign a shortcut key you can use to watermark your work.

#target photoshop;  
app.bringToFront();  
var logoFile = "~/Desktop/JJMack.png"; // Watermark file should be large for resize down works better than up
var LogoSize = 10; // percent of document height to resize Watermark to
var LogoMargin = 1;                                         // percent of Document height the Watermark should have as a margin
placeWatermark(logoFile, LogoSize, LogoMargin);             // Place Watermark  into the bottom right of document
function placeWatermark(Image,Size,Margin){  
  if(!documents.length) return;   // if no document return
  try{  
  var doc = app.activeDocument; // set Doc object to active document
  app.displayDialogs = DialogModes.NO; // Dialog off 
  var strtRulerUnits = app.preferences.rulerUnits; // Save Users ruler units 
  var strtTypeUnits = app.preferences.typeUnits; // Save Users Type units 
  app.preferences.rulerUnits = Units.PIXELS; // work with pixels 
  app.preferences.typeUnits = TypeUnits.PIXELS; // work with pixels 
  var fileObj = new File(Image);                 // the passed file
  if(!fileObj.exists){   // If file does not exits tell user 
  alert(fileObj.name  + " does not exist!");  
  return;  
  }  
  placeFile(fileObj); // Place in file the Watermark png file
  activeDocument.activeLayer.resize(100 ,100,AnchorPosition.MIDDLECENTER); // Insure Place did not scale layer  
  var SB = activeDocument.activeLayer.bounds; // get layers bounds 
  var layerHeight = SB[3] - SB[1]; // get layers height  
  var resizePercent = (100/layerHeight)*(Size/100*doc.height.value); // Percent to resize by 
  activeDocument.activeLayer.resize(resizePercent ,resizePercent,AnchorPosition.MIDDLECENTER);  // Resize width and height by percentage 
  SB = activeDocument.activeLayer.bounds; // get resized layers bounds  
  activeDocument.activeLayer.translate(-SB[0].value,-SB[1].value); // Move resized layer to top left canvas corner 
  var LayerWidth = (SB[2].value - SB[0].value);  
  var LayerHeight = (SB[3].value - SB[1].value);  
  marginSize = Margin/100*doc.height.value; // move resized watermark into the document lower right corner with some margin
  activeDocument.activeLayer.translate((doc.width.value -marginSize - LayerWidth),( doc.height.value -marginSize - LayerHeight));
  }
  catch(e) { alert(e + ': on line ' + e.line); } // inform user of error  
  finally{  
  app.preferences.rulerUnits = strtRulerUnits; // Restore user ruler units  
  app.preferences.typeUnits = strtTypeUnits; // Restore user type units    
  };  
}; 
function placeFile(placeFile) {  
    var desc21 = new ActionDescriptor();  
    desc21.putPath( charIDToTypeID('null'), new File(placeFile) );  
    desc21.putEnumerated( charIDToTypeID('FTcs'), charIDToTypeID('QCSt'), charIDToTypeID('Qcsa') );  
    var desc22 = new ActionDescriptor();  
    desc22.putUnitDouble( charIDToTypeID('Hrzn'), charIDToTypeID('#Pxl'), 0.000000 );  
    desc22.putUnitDouble( charIDToTypeID('Vrtc'), charIDToTypeID('#Pxl'), 0.000000 );  
    desc21.putObject( charIDToTypeID('Ofst'), charIDToTypeID('Ofst'), desc22 );  
    executeAction( charIDToTypeID('Plc '), desc21, DialogModes.NO );  
};  

Did you search in the Search-Field or on google for a second?

–> Try Adobe Bridge or Photoshop Actions to get your single click Watermarks

https://community.adobe.com/t5/bridge/how-to-insert-custom-watermark-in-bridge-cc/td-p/5765248?page=1

https://bellevue-avenue.com/pages/free-watermark-creator-photoshop-action