Hi, You have a beautiful pitcher. First the 1811 should be 1861. E S is Erdmann Schligelmilch. Prufsia is correct for Prussia. The F is double ss in old German writing. Your mark was used 1900-1918. The other numbers have no significance. Just something they do in a factory. This info came from CS Marshalls Porcelain & More who contributes to this forum sometimes. Just google What is ES prufsia and click on his website, and scroll down and read the history. Also you’ll find what R S stands for.