Ramat Rachel is a very curious site. It was founded in the days of Hezekiah, and had boatloads of lmlk impressions (3rd in quantity, after Lachish and Jerusalem), both before and after the Revolt (of 701 BC, of course). It also had a palace with Assyrian Palace Ware on its floors after the destruction of the Hezekian stratum, which, when found in Palestine, is a clear indicator of Assyrian presence, since none of it was found at Tell en-Nasbeh II (Babylonian). It may also be noted the Assyrian-era stratum contained a sherd portraying a man seated on a throne, possibly a king, or, more likely, the governor. This stratum contained numerous Rosette impressions (2nd in quantity, after Jerusalem) After the destruction of this stratum, Persian remains were found, containing the largest number of Yhwd impressions discovered at any site.
To discover the purpose of this site, and, possibly, its identification, we must examine the jar marks it contained. The jar marks with the clearest purpose are the Yhwds. They are surely connected with the Persian government, and extremely likely with the taxation system, possibly being sent to the minor cities to be filled, then sent back to the provincial center. This is supported by their findspots: 93% of Yhwds were found in either Ramat Rachel, the City of David, or Mizpah. It seems, therefore, that Ramat Rachel can, like Jerusalem, be treated as a tax-collection and storage center of Yehud. It might have served as the Persian administrative center to supervise the Jewish one at Jerusalem, roughly half the taxes of Judah supporting each.
It is unknown which Assyrian king established Ramat Rahel VA, but both Sennacherib and Esarhaddon (Ezra 4) are options. While in the Persian administration, Ramat Rahel gained some 200 stamp-impressed jars, it only gained a total of some 50 Rosette impressions, found on the descendants of the lmlk storage jars, which held oil and wine. It is not known whether the Rosette impressions are to be associated with Assyrian or post-Assyrian administration. It is, however, known that Rosette impressions are four times fewer at Jerusalem than the lmlks, fifteen times fewer at Lachish, and over ninety times fewer at Gibeon and Mizpah. It is also known that, unlike the Yhwds, there were four main places where Rosettes were found: firstly, Jerusalem, secondly, Ramat Rachel, thirdly, Lachish, and, fourthly, Azekah. Tel ‘Ira, with only three, might be included, since it is not sufficiently excavated. All the rest come from sites with trade or other types of connections with these. It is clear the Rosette impressions cannot be associated with preparations for any revolt, and the fact they are found along with Assyrian Palace Ware goblets at Ramat Rahel,
which might have been destroyed during Josiah’s passover (it was not destroyed), which corresponded with the accession of Sin-sharra-ishkun of Assyria, Sin-Shara-ishkun’s Uruk campaign, or, less likely, 586 BC. If Ramat Rahel was destroyed in 623 BC (or thereabouts), the Rosette impressions would date to Assyrian Iron IIC, not the Late Iron IIC, as most scholars would place them. Considering the above data, it seems likely that Rosettes served as a part of the Assyrian-supervised taxation network in Judah. It should be noted that five Rosette impressions were traded with the Ekronite city of Timnah, and that Ekron imported great quantities of Judahite oil. It may have been so that (state-owned?) oil producers of the (Hebron?) Hill Country would produce the oil to transport to Ramat Rahel and Jerusalem, where it would be sold to the inhabitants of the city and re-sold to the Shephelah.
As for its beginnings, see my lmlk post. It likely was the main storehouse of state-produced oil, as mentioned in 2 Chronicles 32:28, meant for distribution to the villages and fortresses surrounding it. Since it was never attacked by the Assyrians, the lmlk jars remained there for two and a half thousand years for Aharoni to discover.
UPDATE: Since the fall of Ekron is now dated by me to roughly the same time as that of Jerusalem, I now reject the necessity of dating the Rosettes before Babylonian domination.